United States Court of Appeals
                     For the First Circuit


No. 21-1699

                   UNITED STATES OF AMERICA,

                           Appellee,

                               v.

      LUIS O. PÉREZ-GREAUX, T/N LUIS ORLANDO PÉREZ-GREAX,
                     Defendant, Appellant.


          APPEAL FROM THE UNITED STATES DISTRICT COURT
                FOR THE DISTRICT OF PUERTO RICO

        [Hon. Francisco A. Besosa, U.S. District Judge]


                             Before

                Gelpí, Thompson, and Montecalvo,
                         Circuit Judges.


     Kevin E. Lerman, Research & Writing Attorney, with whom Eric
Alexander   Vos,  Federal   Public   Defender,   and  Franco   L.
Pérez-Redondo, Assistant Federal Public Defender, were on brief,
for appellant.
     David C. Bornstein, Assistant United States Attorney, with
whom W. Stephen Muldrow, United States Attorney, and Mariana E.
Bauzá-Almonte, Assistant United States Attorney, were on brief,
for appellee.


                       September 28, 2023
             GELPÍ, Circuit Judge.

             The contention that an injury can amount to a
             crime only when inflicted by intention is no
             provincial or transient notion.      It is as
             universal and persistent in mature systems of
             law as belief in freedom of the human will and
             a consequent ability and duty of the normal
             individual to choose between good and evil.1

             Defendant-Appellant        Luis             Orlando         Pérez-Greaux

("Pérez-Greaux") was convicted of (1) possession with intent to

distribute     controlled    substances       in     violation        of        

(a)(1) and § 841(b)(1)(B); (2) possession of a firearm in

furtherance of a drug trafficking crime, in violation of 

(c)(1)(A); and (3) possession of a machinegun in furtherance

of a drug trafficking crime, in violation of § 924(c)(1)(A) and

§ 924(c)(1)(B)(ii), which carries a mandatory minimum sentence of

thirty years imprisonment. At trial, the district court instructed

the   jury,    over   Pérez-Greaux's        objection,        that,        to    convict

Pérez-Greaux of § 924(c)(1)(B)(ii), the government need not prove

beyond a reasonable doubt that Pérez-Greaux knew that the firearm

he possessed had the characteristics of a machinegun, rather the

government     only   need   prove   that    the     firearm       was     in     fact   a

machinegun.

             Pérez-Greaux    appeals    his        two     firearm       convictions,

arguing that the district court improperly denied his Federal Rule




      1   Morissette v. United States, 

 (1952).


                                     - 2 -
of Criminal Procedure 29 ("Rule 29") motion for acquittal on each

of these counts because there was (1) insufficient evidence at

trial that the firearm he possessed was truly possessed "in

furtherance of" his drug trafficking offense and (2) insufficient

evidence that he knew the firearm he possessed was a machinegun.

In the alternative, he requests a new trial on the basis that the

district   court    (1) improperly   instructed   the    jury   that    the

government was not required to prove that Pérez-Greaux knew the

firearm he possessed was a machinegun, (2) made a slew of alleged

trial errors that he contends infected his right to a fair trial,

and (3) erred by denying his request for a Franks hearing.             While

we rule against Pérez-Greaux's challenge to the sufficiency of the

evidence and      claims   of alleged pretrial and      trial   error, we

conclude, in a case of first impression, that the jury should have

been instructed about Pérez-Greaux's knowledge of the firearm's

characteristics.      Thus, we vacate Pérez-Greaux's conviction for

possession of a machinegun in furtherance of a drug trafficking

crime and remand for a new trial as to that count.

I.   Background

           Because this case comes to us on a unique posture -- to

review a Rule 29 motion for sufficiency of the evidence and a

motion for a new trial based on claims of prejudicial error as a

result of faulty jury instructions -- we recount the facts only as




                                  - 3 -
necessary to frame the issues on appeal.2         Burgos-Montes, 786 F.3d

at 99.

           According to testimony at trial, on June 1, 2018, Puerto

Rico Police Department ("PRPD") Agent Jose Rivera Vélez ("Agent

Rivera") was surveilling Pérez-Greaux's residence, based on a tip

that he had received from a         confidential informant,       who had

previously supplied him information, when he observed Pérez-Greaux

walk out of his home "carrying a black pistol around his waist."

After    consulting   police   records,   Agent    Rivera   learned   that

Pérez-Greaux did not have a license to carry a pistol and requested

a warrant to search his residence, which was issued.

           On June 5, 2018, PRPD officers and Homeland Security

Investigations   ("HSI")   agents   executed   the    search   warrant   of

Pérez-Greaux's residence in Arecibo, Puerto Rico, and, upon their

arrival, found Pérez-Greaux outside.           When PRPD Agent Carlos

Pérez-Carrasco ("Agent Pérez-Carrasco") informed Pérez-Greaux that

they had a search warrant, Pérez-Greaux responded that he did not

want his family harmed and would hand over what was inside.

Thereafter, Pérez-Greaux led officers to a locked safe in his


     2 We do so because we cannot simultaneously recount the facts
in the light most favorable to the verdict or district court's
ruling -- as would be required by a Rule 29 motion -- and in a
"balanced" manner -- as would be required when we are confronted
with claims of prejudicial error. United States v. Burgos-Montes,

 (1st Cir. 2015). Notwithstanding the limited facts
discussed here, we supply additional key facts as needed when we
discuss each of Pérez-Greaux's claims.


                                 - 4 -
bedroom, which contained three kilograms of cocaine, a digital

scale,    and    other   personal     belongings,      including     firearm

periodicals.     He then led them to his children's bedroom in the

adjoining room, which he said contained a firearm.            Indeed, Agent

Pérez-Carrasco, who stood at 5'6", had little difficulty reaching

a plastic bag, on the top shelf of the closet, containing a .9mm

Glock pistol (wrapped in a rag, inside paper bags), magazines, and

separately packed bullets.

            Pérez-Greaux was questioned by HSI Special Agent Juan

Miranda   ("Agent    Miranda")   at   the   Arecibo    Drug   Unit   in   the

Municipality of Camuy for around two hours.            According to Agent

Miranda's trial testimony, Pérez-Greaux stated that he was storing

the cocaine for a drug supplier, alias "Alex," who he knew from

Rochester, New York.     Pérez-Greaux also disclosed that he had been

working as a drug trafficker since March or April 2018 whereby he

would wrap cocaine with carbon paper, vacuum seal it, and box it,

along with toys and other miscellaneous items, for shipping to the

continental United States via the United States Postal Service

("USPS").       At trial, Agent Miranda recalled seeing a box in

Pérez-Greaux's residence addressed to "Alex Ortiz" in Rochester,

New York.   As to the firearm, Pérez-Greaux gave Agent Miranda two

versions of how he obtained it. First, he said that he had received

the firearm and cocaine from Alex, several days before the search,

at a beach club in Isla Verde, Puerto Rico.           Alex had referred to


                                    - 5 -
the firearm as "a short one with a couple of beans," and told him

to "[j]ust hold on to that while I come back."                  Later on, in the

same interview, Pérez-Greaux relayed a different version about the

firearm, telling Agent Miranda that he had received the firearm

from an "extremely dangerous person" that he had known for eight

years named Marcos, or Marquito Santiago, and that he had no idea

that the firearm operated as a fully automatic handgun.

           An operative superseding indictment charged Pérez-Greaux

with five counts: (1) possession of a firearm in furtherance of a

drug   trafficking     crime;     (2) possession     of     a       machinegun      in

furtherance of a drug trafficking crime; (3) illegal possession of

a   machinegun;    (4) possession     with   the     intent         to   distribute

controlled   substances;      and   (5) possession     of       a   firearm    by    a

convicted felon.      Prior to trial, the government requested the

dismissal of Counts Three and Five.

           A.     The Trial

           On October 15, 2019, Pérez-Greaux's four-day jury trial

commenced on the three remaining counts.

           Trial testimony revealed that, during the search of

Pérez-Greaux's residence, law enforcement also recovered a gun

holster, postage-stamped boxes from the children's bedroom closet,

$600, and five cellphones from Pérez-Greaux's side table.                        Over

Pérez-Greaux's      objections,     the   district     court         allowed     the

government to introduce photographs and screenshots extracted from


                                    - 6 -
the        five        cellphones     in     the        days     before      trial,      using

state-of-the-art            technology.           The extraction revealed images,

pre-dating June 5, 2018, of shipment receipts, toys in plastic

bags, and vacuum sealed bricks (of what appeared to be controlled

substances) and screenshots of package tracking information, money

transfers, and text messages discussing pricing.                          Matthew Johnson,

the    computer          forensic        agent    who    performed        the     extraction,

testified         that     he    could    not    determine       who   had      accessed   the

cellphones, captured the images, or deleted them.

                  At    trial,    Jeffrey        T.   Browder,     a   firearms       expert,

testified that the recovered Glock pistol had been altered to

include an external, automatic sear that caused it to function as

a machinegun.            He noted that he was able to identify the machinegun

alteration because of his training and expertise but confirmed it

by test firing the weapon.

                  At the conclusion of the government's case-in-chief,

Pérez-Greaux moved for judgment of acquittal pursuant to Rule 293

on    the    grounds       that     the    government      had    failed     to    put   forth

sufficient evidence of possession with intent to distribute a

controlled substance, failed to prove the "in furtherance of"

element of the firearm offenses, and failed to offer sufficient



       Federal Rule of Criminal Procedure 29(a) provides that
       3

"[t]he court . . . must enter a judgment of acquittal of any
offense for which the evidence is insufficient to sustain a
conviction."


                                             - 7 -
evidence that he knew that the weapon in his home was a machinegun.

The district court denied the motion.

            As previewed and will soon be discussed in greater

detail, the district court also denied Pérez-Greaux's request that

the jury be instructed that, to convict him of possession of a

machinegun       in    furtherance    of   a   drug    trafficking    crime,   the

government had to prove he "had knowledge of the characteristics

that made the weapon a machinegun."             The district court concluded,

as a matter of law, that § 924(c)(1)(B)(ii) does not include "an

implicit subjective mens rea requirement."

            Ultimately, the jury convicted Pérez-Greaux on all three

counts tried.

            B.        Renewed Rule 29 Motion

            Following the verdict, Pérez-Greaux renewed his Rule 29

motion, which the district court again denied, finding that the

evidence     presented        at     trial     sufficiently      supported     the

convictions.          In its written decision, the district court first

held that, with respect to possession with intent to distribute

cocaine,     a    reasonable       juror     could    infer   that   Pérez-Greaux

knowingly        possessed    a    controlled        substance   after   he    led

Agent Pérez-Carrasco to the safe in his bedroom and identified the

substance in it as cocaine and that he had an intent to distribute

those drugs given his admission of working as a drug trafficker

and the presence of boxes, stamps, and shipping receipts in his


                                       - 8 -
home.   United States v. Pérez-Greaux, 

, 136-37

(D.P.R. 2020).

            As to possession of a firearm "in furtherance of" drug

trafficking, the district court held that "objective factors,"

such as being seen with a weapon outside his home and keeping the

weapon in close proximity to where he stored drugs in his home,

"tip[ped] the scale" in favor of there being sufficient evidence

that he possessed the firearm to protect the drugs.               

.    It also noted that a reasonable jury could have found that

Pérez-Greaux     furthered      a   drug      trafficking    crime   when      he

transported the firearm and drugs back to his home in Arecibo from

his meeting with Alex in Isla Verde.            

.    Finally, as

to possession of a machinegun in furtherance of drug trafficking,

the district court, finding no circuit precedent directly on point,

found that the jury instructions were proper, such that the

defendant   need   not   know   the    firearm    was   a   machinegun   for   a

conviction under § 924(c)(1)(B)(ii), and that there was sufficient

evidence that Pérez-Greaux possessed a machinegun based on the

firearms expert's identification of the weapon as a machinegun.

Id. at 140-46.

            Subsequently, the district court sentenced Pérez-Greaux

to 438 months in prison, followed by five years of supervised

release.    This appeal timely followed.




                                      - 9 -
II.     Discussion

            On appeal, Pérez-Greaux only challenges his firearms

convictions.      In addition to contesting the denial of his renewed

Rule 29 motion and jury instruction requests, he asserts that the

district court erred in three evidentiary rulings -- precluding

defense witness testimony, precluding cross-examination of Agent

Miranda on Pérez-Greaux's mens rea statements, and by admitting

images extracted from cell phones in Pérez-Greaux's residence,

along    with   opinion   testimony     that   these    materials   evidenced

specific prior illegal conduct -- all of which denied him the right

to a fair trial, that prosecutorial misconduct in closing arguments

violated    his   Fifth   and   Sixth   Amendment      rights,   and that   the

district court erred in denying his request for a Franks hearing.

Finally, he asserts that, cumulatively, these errors undermined

his right to a fair trial.

            While we ultimately conclude that there was sufficient

evidence for a reasonable jury to convict Pérez-Greaux on both

firearm counts, and thereby affirm the denial of his Rule 29

motion, we also conclude that the jury was improperly instructed

as to the mens rea element of the machinegun crime.               For reasons

we will explain forthwith, the government was required to prove,

beyond a reasonable doubt, that Pérez-Greaux knew that the firearm

he possessed had the characteristics of a machinegun.                 We thus

vacate his conviction for possession of a machinegun in furtherance


                                   - 10 -
of a drug trafficking crime and remand for a new trial as to that

count.

             When a defendant raises both a challenge to a jury

instruction and to the sufficiency of the evidence to support his

conviction, we usually address the sufficiency of the evidence

first, because if the defendant prevails on the insufficiency

argument, then we need not explore any of the other trial errors

raised.      See United States v. Godin, 

 (1st Cir.

2008).    "[O]nce the reviewing court has found the evidence legally

insufficient" to support a conviction, "[t]he Double Jeopardy

Clause precludes a second trial." United States v. Maldonado-Peña,

4   

   (1st   Cir.   2021)    (quoting    United      States   v.

Montijo-Maysonet, 

 (1st Cir. 2020)).               However, when

(as here) the challenge to the jury instruction focuses on an

allegedly missing element from the charge, we address that legal

argument first.         See Godin, 

.       If we agree with

the defendant about the alleged instructional error, then we

normally move on to the sufficiency arguments before determining

whether the instructional error was harmless.             

.     As such,

we   begin   our    discussion   with   the    alleged    error   in    the   jury

instructions, then address the Rule 29 motion for sufficiency of

the evidence, and finally dispense with the rest of Pérez-Greaux's

claims, concluding that none of them warrant a new trial.




                                      - 11 -
          A. JURY INSTRUCTIONS FOR POSSESSION OF A MACHINEGUN IN
          FURTHERANCE OF A DRUG TRAFFICKING CRIME, 

(c)(1)(B)(ii)

          We begin by addressing why the jury should have been

instructed that the government needed to prove Pérez-Greaux had

knowledge that the firearm in question had the characteristics of

a machinegun in order to find him guilty of possessing a machinegun

in furtherance of drug trafficking.    In broad terms, Pérez-Greaux

contends that the strong presumption in favor of finding scienter,4

principles of proportional culpability, standards of statutory

interpretation, and Supreme Court and First Circuit case law compel

this conclusion.   The government counters that the presumption in

favor of scienter is inapplicable here, that the plain language of

the statute does not contain a mens rea requirement, and that the

case law that Pérez-Greaux cites to support his position is

unavailing.   We review the claim de novo, 

, mindful that

it is an issue of first impression in our circuit.

          In 2010, the Supreme Court held that the machinegun

provision of § 924(c)(1)(b)(ii) is an element of the § 924(c)

offense, not just a factor to be considered at sentencing, but

"expresse[d] no views on the point" whether a defendant "must be

aware of the weapon's characteristics."   United States v. O'Brien,




     4Scienter involves "the degree of knowledge necessary to make
a person criminally responsible for his or her acts."     Ruan v.
United States, 

 (2022).


                              - 12 -


, 222, 235 (2010).         Peeling back the layers of

complexity, the question before us is simple:   Did Congress intend

to make a conviction for the possession of a machinegun under

§ 924(c)(1)(B)(ii) a strict liability crime? The D.C. and Eleventh

Circuits are the only circuits that have considered the issue since

O'Brien and, constrained by their own circuit precedent, both have

answered yes.   See United States v. Haile, 

(11th Cir. 2012); United States v. Burwell, 

 (D.C.

Cir. 2011), reh'g en banc granted, judgment vacated (Oct. 12,

2011), opinion reinstated and aff'd, 

 (D.C. Cir.

2012). Our review of the statute, and both Supreme Court and First

Circuit case law, however, leads us to the opposite result.

          Proof of mens rea "requires proof 'that the defendant

know the facts that make his conduct illegal.'"   United States v.

Ford, 

 (1st Cir. 2016) (quoting Staples v. United

States, 

 (1994)); id. at 70 ("Customarily, the

mens rea element is satisfied if the defendant 'know[s] the facts

that make his conduct fit the definition of the offense.'" (quoting

Staples, 

 n.3) (alteration in original)).   Whether

§ 924(c)(1)(B)(ii) requires that a defendant know that the firearm

possessed has the characteristics of a machinegun is a question of

statutory interpretation and, because "[t]he definition of the

elements of a criminal offense is entrusted to the legislature,

particularly in the case of federal crimes," such an interpretation


                              - 13 -
requires an "inference of the intent of Congress."          Staples, 

 (alteration in original) (first quoting Liparota v.

United States, 

 (1985); and then quoting United

States v. Balint, 

, (1922)).          We thus begin, as

always, with the language of the statute.

            A    "machinegun,"   as   defined   by   § 921(a)(24),   which

borrows the definition of a machinegun from the National Firearms

Act, is "any weapon which shoots, is designed to shoot, or can be

readily restored to shoot, automatically more than one shot,

without manual reloading, by a single function of the trigger."5

(b).      In other words, "a fully automatic weapon

[is one] that fires continuously with a single pull on the trigger"

and stands in contrast to a semi-automatic firearm, which "chambers

a new round automatically but requires a new pull on the trigger

to fire."       United States v. O'Brien, 

, 922 n.1 (1st

Cir. 2008), aff'd, 

 (2010).




     5   The statute further provides that:

            The term shall also include the frame or
            receiver of any such weapon, any part designed
            and intended solely and exclusively, or
            combination of parts designed and intended,
            for use in converting a weapon into a
            machinegun, and any combination of parts from
            which a machinegun can be assembled if such
            parts are in the possession or under the
            control of a person.

(b).


                                  - 14 -
         Turning to the text of § 924, we note that it is entitled

"Penalties" and "is elaborate, lengthy and far from homogenous in

character."     Id.   at 922.   Section   924(c)(1)(A) provides for

mandatory minimum sentences for any person who "uses or carries a

firearm" "during and in relation to any crime of violence or drug

trafficking crime" or any person who "possesses a firearm" "in

furtherance of" a crime of violence or drug trafficking crime.6


    6 Section   924(c)(1)(A) and (B) are reprinted below:

              (c)(1)(A) Except to the extent that a
         greater minimum sentence is otherwise provided
         by this subsection or by any other provision
         of law, any person who, during and in relation
         to any crime of violence or drug trafficking
         crime (including a crime of violence or drug
         trafficking crime that provides for an
         enhanced punishment if committed by the use of
         a deadly or dangerous weapon or device) for
         which the person may be prosecuted in a court
         of the United States, uses or carries a
         firearm, or who, in furtherance of any such
         crime, possesses a firearm, shall, in addition
         to the punishment provided for such crime of
         violence or drug trafficking crime--
              (i)   be   sentenced   to   a   term   of
         imprisonment of not less than 5 years;
              (ii) if the firearm is brandished, be
         sentenced to a term of imprisonment of not
         less than 7 years; and
              (iii) if the firearm is discharged, be
         sentenced to a term of imprisonment of not
         less than 10 years.

         (B) If the firearm possessed by a person
         convicted of a violation of this subsection--
              (i)   is    a    short-barreled   rifle,
         short-barreled   shotgun,   or  semiautomatic
         assault weapon, the person shall be sentenced



                                - 15 -
Subsection (i) provides for a mandatory sentence of at least five

years   for    such   an    offense,     and     subsections   (ii)    and   (iii),

respectively,      provide        for   seven    years    if   the    "firearm   is

brandished," and ten years if the "firearm is discharged."                       And

§ 924(c)(1)(B) further provides minimum sentences for possession

of a firearm, a minimum of ten years if the firearm in question is

a "short-barreled rifle, short-barreled shotgun, or semiautomatic

assault weapon," and at least thirty years if it is a "machinegun

or a destructive device[] or is equipped with a firearm silencer

or firearm muffler."            Id. § 924(c)(1)(B)(i), (ii).

              The plain text before us then is silent as to mens rea.

The government would have us conclude that without explicit mens

rea there can be none, but by now it is well-established that

"silence on this point by itself does not necessarily suggest that

Congress      intended     to    dispense   with    a    conventional    mens    rea

element."      Staples, 

; see also Rehaif v. United

States, 

 (2019) (stating that "the presumption

in favor of scienter" applies "even when Congress does not specify




              to a term of imprisonment of not less than 10
              years; or
                   (ii) is a machinegun or a destructive
              device, or is equipped with a firearm silencer
              or firearm muffler, the person shall be
              sentenced to a term of imprisonment of not
              less than 30 years.

.


                                        - 16 -
any scienter in the statutory text," and "applies with equal or

greater force when Congress includes a general scienter provision

in the statute itself"); Elonis v. United States, 

 (2015) ("We have repeatedly held that 'mere omission from a

criminal enactment of any mention of criminal intent' should not

be read 'as dispensing with it.'" (quoting Morissette, 

)); Morissette, 

 ("We hold that mere omission

from § 641 of any mention of intent will not be construed as

eliminating that element from the crimes denounced."); United

States   v.    X-Citement   Video,   Inc.,    

   (1994)

(interpreting a statute to include a scienter requirement even

where "the most grammatical reading of the statute" did not support

one); United States v. U.S. Gypsum Co., 

 (1978)

("Certainly far more than the simple omission of the appropriate

phrase from the statutory definition is necessary to justify

dispensing with an intent requirement.").

                                     ***

            Finding no explicit expression of congressional intent

as to mens rea within the plain text of the statute, we would

generally turn to legislative history and statutory structure to

determine     congressional   intent,      but,   in    this    case,     neither




                                 - 17 -
provides guidance one way or another.7                 As such, today's decision

requires that we traverse the Supreme Court's treatment of mens

rea to decipher whether statutes like the one before us should be

construed as containing a presumption of mens rea.                         While the

Supreme Court's jurisprudence on the precise issue that we confront

is unsettled, our decision, as we explain today, is in line with

the Court's case law, as well as with the recognized principles of

proportionality (given the thirty-year mandatory minimum imposed

by the statute), which animates the Supreme Court's mens rea

analysis.

                 There    are    a   number   of    cases     establishing   that    a

presumption        of     mens   rea   underlies    federal     criminal   statutes.

Staples, 

 ("[T]he existence of a mens rea is the

rule       of,   rather     than     the   exception    to,    the   principles     of

Anglo-American criminal jurisprudence." (quoting U.S. Gypsum Co.,

)).           The Court explicitly addressed the presumption

in Morissette where it considered a statute criminalizing the

conversion        of     government    property     after   Morissette     took   bomb




       7The statute's legislative history does not appear
instructive for the present case given that the one change made to
the statute in 1998 was seemingly minimal. See Castillo v. United
States, 

 (2000) (detailing some of the
legislative history of § 924(c)).    While the government offers
that the statute's structure counsels against a finding of mens
rea because certain other provisions of the statute do include an
explicit mention of mens rea, we are not persuaded that we can end
the inquiry here.


                                           - 18 -
casings he believed had been abandoned from government property.

.        The Court applied the presumption that the

statute contained a mens rea requirement and found that Morissette

could not be punished because he did not know that the property

belonged to the government, reasoning that failure to apply the

presumption would "sweep out of all federal crimes, except when

expressly preserved, the ancient requirement of a culpable state

of mind."    

.

            While   the   statute   in   Morissette    contained   the   term

"knowingly," such that the Court need only determine whether it

reached the provision regarding conversion of government property,

the Court has also applied the presumption to statutes that are

otherwise silent on mens rea.         For instance, in U.S. Gypsum Co.,

the Court expressed that it was averse to reading the Sherman

Anti-Trust Act as dispensing with a mens rea requirement because

of "the simple omission of the appropriate phrase [mens rea] from

the statutory definition."       

.       See also Carter v.

United States, 

 (2000) (explaining that the

lack of explicit mention of mens rea in a statute criminalizing

the   taking   of   bank    property     by   "force   and   violence,    or

intimidation," still required "proof of knowledge" as to the act

for conviction); Posters 'N' Things, Ltd. v. United States, 

 (1994) (applying presumption of mens rea to a

statute, thereby requiring defendant to have had knowledge that


                                    - 19 -
the materials possessed were drug paraphernalia likely to be used

with illegal drugs); Staples, 

 (holding

that a presumption of mens rea applies to statute otherwise silent

on knowledge and thus requiring defendant to have known that the

gun was an automatic); United States v. Bailey, 

, 406

n.6 (1980) (reasoning that simply because there is no explicit

mention of mens rea does not mean the offense is a "'strict

liability' crime for which punishment can be imposed without proof

of any mens rea at all").

          Moving   on   to   how    the     Supreme    Court   applies   the

presumption of mens rea, we note that it has drawn an important

distinction between elements of an offense and sentencing factors.

An element of an offense is a "fact necessary to constitute the

crime," Almendarez-Torres v. United States, 

(1998),   while     sentencing        factors         generally    "involve

characteristics of the offender -- such as recidivism, cooperation

with law enforcement, or acceptance of responsibility," O'Brien,

560 U.S. at 227 (citation omitted).         Elements of a crime must be

proven to a jury beyond a reasonable doubt, while sentencing

factors only need to be proven to a judge by a preponderance of

the evidence.   Id. at 224.    Immediately applicable here are the

Supreme Court's decisions in United States v. Dean and O'Brien,

which, together with principles of criminal law, stand for the

proposition that the presumption of mens rea applies to elements


                                   - 20 -
of an offense.        See Dean v. United States, 

 (2009);

O'Brien, 560 U.S. at 227.

              At   issue   in    Dean    was   § 924(c)(1)(B)(ii)'s     neighbor

provision, § 924(c)(1)(A)(iii),8 which imposes a mandatory ten

years' imprisonment when a defendant, during a crime of violence

or drug trafficking, "discharge[s]" a firearm.                

.

In reaching a decision as to whether the discharge provision

required proof of intent, the Supreme Court drew a distinction

between sentencing factors and elements of the offense and held

that, because § 924(c)(1)(A)(iii) was a sentencing factor, proof

of intent was not required.             Dean, 

.

              The Court confirmed the importance of this distinction

in O'Brien where, in assessing whether the automatic character of

a firearm as outlined in § 924(c)(1)(B)(ii) must be proven to the

jury beyond a reasonable doubt, the Court again drew a distinction

between elements of a crime and sentencing factors.                  560 U.S. at

221.       The Supreme Court affirmed this court and held that the

government needed to prove beyond a reasonable doubt that the

firearm in question was a machinegun given, in part, because "[t]he

immense      danger   posed     by   machineguns,    the   moral    depravity   in

choosing the weapon, and the substantial increase in the minimum

sentence provided by the statute."               Id. at 230, 235.    In reaching




       8   See note 6 for the full statutory text.


                                        - 21 -
its conclusion, the Court emphasized the potential unfairness that

could   result    from   classifying   the   machinegun    provision    as   a

sentencing factor because it could very well produce a conflict

between the judge and the jury (given that the jury could find

that the defendant used a pistol and the judge at sentencing could

find that it was a machinegun) and result in a "drastic, sixfold

increase" in the severity of the sentence (from the five-year

mandatory minimum for a firearm to the thirty-year minimum for a

machinegun).      Id. at 228-29.

              O'Brien thus eliminated the underlying assumption that

other circuits had previously relied on to justify excluding a

mens    rea   requirement    from   possession   of   a   machinegun:   that

subsection (c)(1)(B)(ii) was a sentencing factor that did not

require evidence of mens rea.          Taken together, Dean and O'Brien

thus indicate that the presumption of mens rea applies to elements

of an offense, but generally does not apply to sentencing factors.

See Burwell, 

 (Kavanaugh, J., dissenting) ("If a

fact is an element of the offense and not a sentencing factor, the

presumption [of mens rea] applies.").

              O'Brien left open whether the government needed to prove

that the defendant knew that the firearm in question included the

characteristics relevant to the section charged, the precise issue

we confront today.       See 560 U.S. at 222 ("The issues in the present

case do not require the Court to consider any contention that a


                                    - 22 -
defendant who uses, carries, or possesses a firearm must be aware

of the weapon's characteristics.           This opinion expresses no views

on the point.").         However, because mens rea presumptively applies

to elements of a crime and because the Supreme Court determined

that the automatic character of a firearm is an element of the

offense, rather than a sentencing factor, it only follows that

§ 924(c)(1)(B)(ii) is subject to the mens rea presumption.                   See

Model Penal Code § 2.02(4) ("When the law defining an offense

prescribes the kind of culpability that is sufficient for the

commission    of    an    offense,   without    distinguishing       among   the

material elements thereof, such provision shall apply to all the

material elements of the offense, unless a contrary purpose plainly

appears.").

            The    government     pushes    back   and     asserts   that    the

presumption of mens rea is inapplicable to § 924(c)(1)(B)(ii)

because this statute includes the predicate crime of either drug

trafficking or a crime of violence and "does not punish conduct

that would otherwise be innocent."             We disagree for a number of

reasons.    The Supreme Court has indeed applied the presumption to

cases where a statute criminalizes otherwise innocent conduct.

See, e.g., Liparota, 

 (ruling that statute

criminalizing      the    acquisition   and    possession    of   food   stamps

contained     a    mens    rea   requirement    that     defendant   knew    his

acquisition or possession was unauthorized); Morissette, 342 U.S.


                                     - 23 -
at 276 (holding that statute criminalizing converting government

property required criminal intent).         The Court has also often

"emphasized scienter's importance in separating wrongful from

innocent acts."   Rehaif, 

 (collecting cases).

           Nevertheless, it does not necessarily follow that the

presumption only applies there and nowhere else.               Notably, the

Supreme Court has previously applied the presumption of mens rea

to a federal criminal statute that included a predicate crime.

See   Flores-Figueroa   v.   United    States,   

   (2009).

Flores-Figueroa involved a statute that imposed two additional

years of mandatory imprisonment to defendants who -- while engaged

in the commission of certain crimes already punishable by prison

time,     including     theft     of      government        property      or

fraud -- "knowingly     transfer[],    possess[],      or   use[],   without

lawful authority, a means of identification of another person."

 at 647    (quoting 18 U.S.C. § 1028A(a)(1)).               Because this

statutory provision already included the predicate crime of theft

of government property or fraud, according to the government's

argument, the presumption should not apply.         However, the Supreme

Court did not rule as such.     Instead, it held that the government

was required "to show that the defendant knew that the 'means of

identification' he or she unlawfully transferred, possessed, or

used, in fact, belonged to 'another person.'"                  Id.   (quoting




                                - 24 -
§ 1028A(a)(1)).     Thus, Flores-Figueroa directly undermines the

government's argument.

           Furthermore,       the   Supreme    Court    has     not    explicitly

articulated a rule dictating that the presumption will only apply

where innocent conduct is at stake.               Instead, the Court has

repeatedly stated that criminal offenses that dispense with a mens

rea   requirement   are   "disfavored."         Staples,      511     U.S    at   606

("Relying on the strength of the traditional rule, we have stated

that offenses that require no mens rea generally are disfavored.");

U.S. Gypsum Co., 

 ("While strict-liability

offenses are not unknown to the criminal law and do not invariably

offend constitutional requirements, the limited circumstances in

which Congress has created and this Court has recognized such

offenses, attest to their generally disfavored status." (internal

citations omitted)). And this makes sense since "the understanding

that an injury is criminal only if inflicted knowingly 'is as

universal and persistent in mature systems of law as belief in

freedom of the human will and a consequent ability and duty of the

normal individual to choose between good and evil.'"                  Rehaif, 

 (quoting Morissette, 

).                       Further,

the   Supreme   Court   has    made    clear   that    "[t]he    heart       of   the

retribution rationale is that a criminal sentence must be directly

related to the personal culpability of the criminal offender."

Tison v. Arizona, 

 (1987).              Doing away with the


                                      - 25 -
defendant's knowledge of the characteristics of the firearm would

make possessing a machinegun a strict liability crime, which would

eliminate the longstanding "concurrence of an evil-meaning mind

with an evil-doing hand."           Morissette, 

.

            Moreover,       this    reasoning     is    in     accord      with    basic

principles of federal criminal law.               Merely because a defendant

has already engaged in wrongdoing does not mean that the government

should   not    be   held   to     the   burden   of    demonstrating           that   the

defendant      consciously       chose    between      two     distinct     types      of

firearms. Why should this underlying offense trigger an additional

thirty years when Congress punished that conduct elsewhere?                             In

other words, while a § 924(c)(1)(B)(ii) defendant might be guilty

of the predicate offense -- that is, possession of a firearm in

furtherance of a crime of violence or drug trafficking crime -- we

see no logic in dispensing with the requirement of a vicious will

for the second offense where the only additional element is that

the firearm is a machinegun.             This is particularly true where the

type   of   firearm    chosen      can    potentially        result   in    a     sixfold

sentencing increase.          Thus, the government's arguments to the

contrary are not persuasive.

                                          ***

            Having established that the presumption applies here, we

are still required to ask whether there is some specific indication

from Congress that it should not apply to § 924(c)(1)(B)(ii).


                                         - 26 -
Staples, 511 U.S. at 606 ("[S]ome indication of congressional

intent, express or implied, is required to dispense with mens rea

as an element of a crime.").                   We see no indication here that

Congress       sought   to   take    the       extraordinary    step    of    making

§ 924(c)(1)(B)(ii) a strict liability offense.                 The Supreme Court

has said that there are certain cases where courts should depart

from the presumption of a culpable mental state.                For example, the

Supreme Court has declined to apply the presumption in favor of

scienter for some "activities affecting public health, safety, and

welfare." United States v. Freed, 

 (1971) (citing

Morissette, 

).              The Court has also indicated that

congressional silence concerning the mental element of the offense

may signify that Congress intended to dispense with traditional

mens     rea    requirements    when       a     statutory   provision       involves

something like a dangerous weapon of war.                See, e.g., id. at 609-10

(holding that Congress considered that the potential danger of

owning     an    unregistered       hand       grenade   outweighed    potentially

penalizing an innocent grenade owner).               This reasoning is premised

on the understanding that individuals should be on notice that

their conduct is subject to regulation such that no mens rea need

be read into the statutory provision. The additional consideration

at play here, however, is the principle of proportionality.

               Indeed, our decision accords with the Supreme Court's

jurisprudence      on   proportionality.             Staples   offers    guidance.


                                       - 27 -
There, the Supreme Court considered a nearly identical statute to

the    one    before   us -- 

(d) -- which        makes    it

unlawful for a defendant "to receive or possess" a firearm that is

not    registered      to     them,    § 5861,       including    a   machinegun,

§ 5845(a)(6), and includes a penalty of up to ten years.                    Staples

was charged with possessing a rifle that "had been filed away,

and . . . assembled with an M-16 selector switch and several other

M-16 internal parts," making it a machinegun.                  Staples, 

.       He argued that he was ignorant as to the rifle's

ability to fire automatically since, for him, it had only fired

semiautomatically.          

.      As such, he proposed that the

jury be instructed that the government was required to prove that

he knew that the gun would fire fully automatically.                  

              While the plain text of § 5861(d) does not contain an

explicit mens rea requirement, the Court extended the presumption

of mens rea to the provision, concluding that a defendant must

know that the firearm is automatic.                Id. at 602, 605.        In doing

so,    the   Court   emphasized       that   the     "harsh"   ten-year    "penalty

attached to § 5861(d) suggests that Congress did not intend to

eliminate a mens rea requirement for violation of the section"

because "[h]istorically, the penalty imposed under a statute has

been    a    significant     consideration      in    determining     whether     the

statute should be construed as dispensing with mens rea."                    Id. at

616, 619.      While small penalties might complement the absence of


                                       - 28 -
mens rea, the court noted that "[i]n a system that generally

requires a 'vicious will' to establish a crime, imposing severe

punishments for offenses that require no mens rea would seem

incongruous."       Id.    at   616-17   (internal       citations    omitted).

Moreover, it would be inconsistent to hold that no mens rea is

required in § 924(c)(1)(B)(ii) while holding that § 5861(d) does

contain a mens rea requirement since both statutes employ the same

definition of a "machinegun."

          This reasoning accords with the Court's decisions in

X-Citement Video (considering 

), U.S. Gypsum Co.

(construing     criminal    violations       of   the    Sherman     Act),   and

Morissette    (involving        a   statute       criminalizing      converting

government property).      Each case involved the interpretation of a

federal statute imposing a maximum sentence of ten years, three

years, and one year, respectively.           In each instance, the Supreme

Court highlighted the severity of the punishment imposed, noting

that the "penalty is high," Morissette, 

, that

"harsh penalties loom[ed] equally large," X-Citement Video, 

, and that "[t]he severity of the[] sanctions provide[d]

further   support    for    [the]    conclusion         that   the   [statutory

provision] should not be construed as creating strict-liability

crimes," U.S. Gypsum Co., 

 n.18.

          Such is the case here.         The penalty at issue is no light

sentence as it is an additional thirty years on top of the


                                    - 29 -
punishment for the underlying crime.                   That is, it is triple that

considered      in     Staples     and      X-Citement     Video,    ten    times    that

considered in U.S. Gypsum Co., and thirty times that considered in

Morissette.      Because a minimum of thirty years hang in the balance

for defendants charged with § 924(c)(1)(B)(ii), it does not make

sense that Congress would impose such a draconian sentence for a

crime    and    not    hold     the   government      to   the    burden    of     proving

knowledge of the specific characteristics of the firearm that make

the defendant culpable under that particular section. Common sense

and the above-referenced cases indicate that Congress could not

have    intended      a   strict      liability      crime   for     a    crime    with   a

thirty-year sentence attached.

               Ultimately, "[t]he purpose and obvious effect of doing

away with the requirement of a guilty intent is to ease the

prosecution's path to conviction."                   Morissette, 

.

But where thirty years are at stake, holding the government to its

burden    of     establishing         the     defendant's     knowledge       beyond      a

reasonable doubt is paramount to maintaining our understanding of

the choice between good and evil.                    Holding otherwise would mean

that a defendant "can be subject to [an additional thirty years]

imprisonment,         despite    absolute      ignorance     of     the    gun's    firing

capabilities, if the gun [used in a crime of violence or drug

trafficking offense] turns out to be an automatic."                        Staples, 

.         And we know that ignorance is indeed possible since


                                            - 30 -
"virtually any semiautomatic weapon may be converted, either by

internal modification or, in some cases, simply by wear and tear,

into a machinegun."          

    As such, these Supreme Court cases and

the shared definition of a machinegun between § 924(c)(1)(B)(ii)

and the statute at issue in Staples support our conclusion that

the jury should have been instructed that, to convict of possession

of a machinegun in furtherance of drug trafficking, the government

had to prove Pérez-Greaux knew the firearm had the characteristics

of an automatic weapon.

             This    ruling        accords     with    this    court's    previous

observations of the importance of considering the severity of the

penalty as outlined by Staples.              For instance, in United States v.

Nieves-Castaño,       we     considered       a   conviction    under    

(o), which makes it "unlawful for any person to transfer or

possess a machinegun."         

, 599 (1st Cir. 2007) (quoting

§ 922(o)).     At issue was whether the government had proved that

the defendant knew the rifle in question, an AK-47, had the

characteristics of a machinegun to withstand conviction since

§ 922(o) contains a mens rea requirement.                      Id. at 598.      We

ultimately reversed the conviction on the basis of insufficient

evidence of the defendant's mens rea.                 Id. at 602.   While we did

not   have   to     decide    whether     § 922(o)      contained   a    mens   rea

requirement because the government conceded that the "Staples's

scienter requirement also applies to prosecutions under 18 U.S.C.


                                       - 31 -
§ 922(o)," we noted that this concession was correct given the

"harsh penalty" attached to § 922(o), up to ten years.                     Id. at

600.

            Overall, we think that "if Congress had intended to make

outlaws of gun owners who were wholly ignorant of the offending

characteristics of their weapons, and to subject them to lengthy

prison terms, it would have spoken more clearly to that effect."

Staples, 

.

                                         ***

            We    recognize       that   other      circuits   have    come   out

differently when confronted with the § 924(c)(1)(B)(ii) mens rea

issue.   Prior to the Supreme Court's decision in O'Brien, every

court of appeals to consider the issue held that the statute did

not contain a mens rea requirement.             However, those decisions were

based on the presumption that § 924(c)(1)(B)(ii) was a sentencing

enhancement      and   not   an   element      of   the   crime,   which   O'Brien

debunked.    See, e.g., United States v. Ciszkowski, 

 (11th Cir. 2007) ("[B]ecause § 924(c) is an enhancement

statute, it does not require proof of 'particularized knowledge'

of the weapon['s] characteristics."); United States v. Gamboa, 

 (8th Cir. 2006) ("Because the facts concerning the

type of firearm used in § 924(c)(1) are sentencing factors, and

not elements of the offense, we also conclude that the United

States was not required to show that Gamboa subjectively knew that


                                     - 32 -
the firearm was a machinegun."); United States v. Brown, 

, 1255 n.9 (10th Cir. 2005) ("Knowledge that a gun is a machine

gun is not an element of the third count against Mr. Brown for

carrying a gun during and in relation to a drug trafficking

crime."); United States v. Morrow, No. CRIM.A. 04-355CKK, 

, at *4 (D.D.C. June 20, 2005), aff'd sub nom. Burwell, 

 (D.C. Cir. 2011), reh'g en banc granted, judgment vacated

(Oct. 12, 2011), opinion reinstated and aff'd, 

 (D.C.

Cir. 2012) ("[T]he type of a firearm used or carried under § 924(c)

[is] a sentencing enhancement rather than an element of the offense

and, therefore, a separate mens rea for the type of weapon need

not be proven." (quoting United States v. Nava-Sotelo, 

 (10th Cir. 2003)) (second alteration in original)); see

also United States v. Eads, 

 (10th Cir. 1999)

("[W]e agree with the Fifth Circuit that the type of firearm used

or carried is a sentencing enhancement rather than an element of

the offense . . . .").

          As we mentioned earlier, the only two Circuits that have

considered this issue post O'Brien are the D.C. and Eleventh

Circuits, which held that the statutory provision did not contain

a mens rea requirement.   See Burwell, 

; Haile, 

.   Both decisions were based, in large part, on each

circuit's precedent, to which we are not bound.   For instance, in

Haile, the Eleventh Circuit reasoned that because it had previously


                              - 33 -
held in Ciszkowski that § 924(c)(1)(B)(ii) did not require proof

of the defendant's knowledge of the weapon's characteristics, and

because O'Brien did not explicitly overrule Ciszkowski, it was

bound "[u]nder the prior precedent rule . . . to follow [] prior

binding precedent 'unless and until it is overruled by [the] court

en banc or by the Supreme Court.'" Haile, 

 (quoting

prior cases).    As such, and without discussing the merits of the

claim, the Eleventh Circuit held that the government was not

required to prove knowledge.

            Similarly, in Burwell, the D.C. Circuit held en banc

that, given the court's prior decision in Harris v. United States,

 (2002) and the "high burden imposed on any party who

urges [the] [c]ourt to depart from the principle of stare decisis,"

it     simply   could   not     "set   aside   a    circuit       precedent

that . . . governed     [its]   interpretation     for   twenty    years."

Burwell, 

.       Because in determining congressional

intent "[n]othing [in Harris] turned on whether the machinegun

provision was considered an element of the offense or a sentencing

factor," the Burwell court insisted it was bound by its circuit

precedent to find no mens rea requirement.         Burwell, 

.    Unlike Haile and Burwell, we write on somewhat of a blank

slate and are not bound by our own circuit precedent holding one

way or the other.




                                  - 34 -
            Our decision today is consistent with prior discussions

within    our   Circuit    even       though    this       is    the   first    time     this

particular issue has been squarely presented to us.                         Recall that,

in O'Brien, we did not answer the question of the defendant's

knowledge.      

.          Two other cases decided after our

court's    decision       in     O'Brien       bolster          our    conclusion        that

§ 924(c)(1)(B)        contains    a    knowledge       requirement.             See   United

States v. Laureano-Pérez, 

 (1st Cir. 2015);

United States v. Rivera-Rivera, 

, 291 n.14 (1st Cir.

2009).

            First, in addressing a challenge to a violation of

§ 924(c)(1)(C)(i),        which        mandates        a        minimum    sentence        of

twenty-five years following a subsequent conviction under this

subsection,      we     held     that     § 924(c)(1)(C)(i)               constitutes       a

sentencing enhancement rather than an element of the offense.

Rivera-Rivera, 

.                     In a footnote, however, we

construed our     earlier        decision in        O'Brien, 

, as

"conclud[ing] that knowing possession of a machine gun is an

element of the crime that must be proven to the jury."                          

 at 291

n.14.     While Pérez-Greaux would have us accept this footnote as

binding    precedent,      we     cannot       do   so      because       the    issue     in

Rivera-Rivera was whether § 924(c)(1)(C)(i), not § 924(c)(1)(B),

was an element of the offense.             See United States v. Starks, 

 (1st Cir. 2017) (finding that certain language was


                                        - 35 -
dicta since "[i]t was presented without analysis and, because it

addressed a broader argument . . . it was not necessary to the

court's conclusion"); Rivera-Rivera, 

 n.14 (stating

in the same footnote, that the issue then before the court did not

"make any allegations regarding the possession of a machine gun").

Notwithstanding that this case did not directly address the issue

now before us, it buttresses our conclusion, since we clearly

arrived at the same conclusion.

           Second   and   more   recently,     in     Laureano-Pérez,    we

considered, among other things, a challenge to convictions for

possession of a machine gun under § 924(c)(1)(B)(ii) and § 922(o).

.     While the court held that there was sufficient

evidence to conclude that the defendant knew he possessed a weapon

having the characteristics which brought it within the definition

of a machinegun, the court assumed that § 924(c)(1)(B)(ii) and

§ 922(o) shared the same mens rea requirement.        Id. at 74-75.     Even

though Laureano-Pérez does not bind us to a specific ruling, it

suggests    that     applying     a       knowledge     requirement      to

§ 924(c)(1)(B)(ii) is in keeping with our prior interpretations

when possession of a firearms is an element of the charged crime.

                                  ***

           Having determined that the district court instructed the

jury in error, we would now typically turn to assessing whether

the error was harmless.      United States v. Fernández-Jorge, 894


                                 - 36 -
F.3d 36, 54 (1st Cir. 2018) ("When jury instructions fail to

account for an element of the crime charged, that error is harmless

only if we can conclude 'beyond a reasonable doubt that the omitted

element was uncontested and supported by overwhelming evidence,

such that the jury verdict would have been the same absent the

error.'" (quoting United States v. Pizarro, 

(1st Cir. 2014)).   Pérez-Greaux briefly asserts that the error was

not harmless, but the government does not address this point in

its briefing.     Instead, at oral argument, the government stated

that if we were to find that the district court failed to give the

appropriate instruction, we "would have to vacate" and remand for

a new trial.      Given this concession, we vacate Pérez-Greaux's

§ 924(c)(1)(B)(ii) conviction and remand his case for a new trial

on this count.9

          B.    SUFFICIENCY OF THE EVIDENCE

          As we noted up front, despite concluding Pérez-Greaux's

conviction under § 924(c)(1)(B)(ii) must be vacated and remanded

for a new trial based on the erroneous jury instruction, we still

address his argument that there was insufficient evidence to prove

he knew the firearm in question had been altered to allow automatic

firing because, if we agree with him, the result would be the


     9 While we vacate and remand for a new trial on Count Two, we
do not ascribe fault to the district court in not giving the jury
the mens rea instruction we now require since at the time of the
trial there was scant guidance from our circuit as to the issue.


                               - 37 -
reversal of the conviction and instructions to dismiss this count

and not simply a remand to the district court for a new trial.

See Godin, 

 (citations omitted).

           Rule 29 provides that a court may acquit a defendant if

the evidence is insufficient to establish factual guilt. We review

a district court's determination on a Rule 29 motion for acquittal

de novo, viewing the evidence in the light most favorable to the

government.     United States v. Bristol-Mártir, 

, 38 (1st

Cir. 2009).     Pérez-Greaux faces a formidable standard.            While we

apply de novo review to preserved sufficiency claims, "[i]t is not

our job to re-weigh the evidence or second-guess the jury's

credibility determinations."          United States v. Bobadilla-Pagán,

 (1st Cir. 2014) (citation omitted).                Instead, we

must   credit   the   government's     witnesses,     draw   all    reasonable

inferences in its favor, and uphold the verdict if it is "supported

by a plausible rendition of the record."               

 (quoting United

States v. Cortés–Cabán, 

 (1st Cir. 2012)).              In other

words, reversal is warranted only if we find that "no levelheaded

jury could have found [Pérez-Greaux] guilty."           

 (quoting United

States v. Guerrier, 

 (1st Cir. 2011)).                   For the

reasons we explain below, we conclude that the government presented

sufficient    evidence   for   the    jury    to   convict   Pérez-Greaux   of

(1) possessing a firearm in furtherance of a drug trafficking crime




                                     - 38 -
and   (2) possessing           a    machinegun     in   furtherance     of   a    drug

trafficking crime.         We address each in turn.

                    1.   Possession of a Firearm in Furtherance of a
                    Drug Trafficking Crime

          We     first         address     Pérez-Greaux's      challenge     to    his

conviction for possession of a firearm "in furtherance of" a drug

trafficking crime.        § 924(c)(1)(A).          To convict Pérez-Greaux under

§ 924(c)(1)(A), the government must establish at trial that he

(1) possessed       a    firearm         (2) in    furtherance    of    (3) a     drug

trafficking     crime.             § 924(c)(1)(A),      (2);   United    States     v.

Gonsalves,    

   (1st   Cir.   2017).     On   appeal,

Pérez-Greaux does not dispute that he possessed a firearm, nor

that he committed a drug trafficking crime.                    Indeed, he himself

led law enforcement to the firearm's precise location when they

entered the home, and there was ample evidence that he engaged in

drug trafficking given that he told Agent Miranda that he had been

working as drug trafficker since March or April of 2018.                           See

United States v. Rodríguez-Martinez, 

 (1st Cir.

2015) ("A finding of constructive possession requires a showing

'that the person knows (or has reason to know) that the firearm is

within easy reach, so that he can take actual possession of it

virtually at will.'" (quoting United States v. Robinson, 

 (1st Cir. 2007))).               Thus, we are only left to determine

whether, as he contends, the evidence is insufficient that he



                                          - 39 -
possessed the firearm "in furtherance of" the undisputed drug

trafficking crime.

            Mere presence of a firearm in an area where a criminal

offense     occurred        is   not   enough      to     sustain        a        conviction,

Bobadilla-Pagán, 

; rather, for a person to possess

a gun "in furtherance of" a drug offense, the government must

establish "a sufficient nexus between the firearm and the drug

crime such that the firearm advances or promotes the drug crime,"

United States v. Ramirez-Frechel, 

 (1st Cir. 2022)

(quoting United States v. Pena, 

 (1st Cir. 2009)).

We analyze "in furtherance of" evidence from both objective and

subjective viewpoints, taking into account that the element lacks

"a settled, inelastic, definition."               

     As to objective factors,

we   consider      "(1) the      proximity    of    the        firearm       to     drugs   or

contraband;        (2) whether     the    firearm        was     easily        accessible;

(3) whether     the    firearm     was    loaded;        and    (4) the           surrounding

circumstances."         Bobadilla-Pagán,           

     (citation

omitted).     A subjective factor could be, for example, evidence

"that a defendant obtained a firearm to protect drugs or proceeds";

but, where subjective indicators are absent, the jury is able to

infer     intent     from    objective      circumstances.               

       (citation

omitted).

            Here, objective factors point in favor of concluding

that the "in furtherance of" element is satisfied.                                First, the


                                         - 40 -
government offered testimony that Pérez-Greaux led law enforcement

to the firearm, which was recovered on the top shelf of his

children's bedroom closet.       This demonstrates that the firearm was

located in the same residence as the drugs.           Had the government

stopped here, this would have been insufficient to satisfy the "in

furtherance of" element since "[t]he mere presence of a firearm in

the area where the drug offense occurred," 

 is not enough.

However, the government also proffered testimony that the firearm

was found in close proximity to the cocaine found in the adjoining

room, was easily accessible since the officer who recovered the

firearm stood at 5'6" and had little difficulty recovering it, and

accompanying    the   firearm,    though   not   necessary    to    uphold   a

conviction, were magazines and bullets.            See United States v.

Mendoza-Maisonet, 

 (1st Cir. 2020) (holding that the

firearm was accessible even though it was in a child's bedroom and

needed to be reached by standing on a chair).        The close proximity

and accessibility of the firearm thereby indicate that a reasonable

jury could draw the inference that there was some connection

between the firearm and the drug trafficking crime.

          Moreover,     we   have    previously    held      that   the   "in

furtherance of" element may be established where there is some

indication that the firearm is possessed "to protect drugs or sales

proceeds."     United States v. Alverio-Meléndez, 

(1st Cir. 2011) (quoting United States v. Marin, 

, 27


                                  - 41 -
(1st Cir. 2008)).   Pérez-Greaux presented shifting stories as to

how he acquired the firearm -- he first told officers that he was

storing it for a drug supplier, alias "Alex," who asked him to

"[j]ust hold on to that while I come back," but later, in the same

interview, Pérez-Greaux said the firearm belonged to someone named

"Marcos" whom he feared.     While Pérez-Greaux's statements as to

how he came to possess the firearm changed, a reasonable jury could

have accepted his initial version of the facts -- that he had

obtained the firearm from Alex -- and inferred that, because Alex

gave him the firearm when he gave him the cocaine, his "taking

possession of the firearm from Alex [w]as advancing or promoting

the drug trafficking."      Pérez-Greaux, 454 F. Supp. 3d at 140.

Moreover, as the district court points out, the jury could have

also inferred that when Alex gave Pérez-Greaux the firearm and

cocaine in Isla Verde, the firearm was used to protect the drugs

as Pérez-Greaux made his way home to Arecibo.   See id. at 140-41.

          Further, the jury could have inferred that he possessed

the firearm to safekeep the drugs and/or proceeds inside his

residence since he used his home to package and ship the cocaine.

See Mendoza-Maisonet, 

 (holding that one such way a

firearm might be said to be possessed "in furtherance of" a drug

crime is for a jury to find that it was possessed to protect the

defendant's drug supply).    Such was the case in Bobadilla-Pagán.

There, the evidence showed that the defendant kept a loaded,


                               - 42 -
unlicensed firearm just a few feet away from drugs in a minivan.

.       While the defendant, like Pérez-Greaux, argued

that the mere presence of the firearm where drugs were kept could

not be said to be "in furtherance of" a drug trafficking crime, we

held that, given "the extremely high bar set for a sufficiency

challenge," those facts, taken together with the jury hearing

testimony    that   "drug    traffickers      often   possess    firearms   for

protection    of    drug    trafficking    activities,"    were    sufficient

evidence for a rational jury to find that the defendant possessed

the firearm "in furtherance of" his drug trafficking activities.

.    Because a jury is entitled to make these inferences,

we cannot say that no level-headed jury could have found otherwise

here.

            Pérez-Greaux insists that the evidence does not move

beyond mere possession.        He argues that the firearm was unloaded

and not easily accessible because it was "packed-up" (since it was

wrapped in bags) and stored in an entirely separate room from the

drugs that were uncovered.         But standing up next to our case law,

these arguments fall flat.         We have previously held that a firearm

was possessed "in furtherance of" a drug crime even when the

firearm was by no means easily accessible. For instance, in United

States v. Grace, we concluded that there was sufficient evidence

to   establish     that    Grace   possessed   the    unloaded    firearm   "in

furtherance of" her drug crimes even though the firearm was stored


                                     - 43 -
in a drawer under her bed, in her bedroom, to protect the drug

supply found in her computer room.          

 (1st

Cir.   2004).     And   in   United     States   v.   Luciano,      we   had   "no

difficulty"     concluding    that    the   defendant's       possession   of    a

firearm to protect his drugs provided a sufficient nexus between

the drugs and the firearm even though the firearms were discovered

in a crawlspace in the defendant's apartment ceiling.               

 (1st Cir. 2003) (concluding sufficient nexus after law

enforcement officers discovered heroin, drug paraphernalia, two

handguns, and two loaded, but detached, magazines in the crawlspace

of the apartment where defendant, who had been arrested on the

street while carrying heroin, had just been, based on the "close

proximity of the firearms and loaded magazines to the significant

stockpile of heroin").        The firearm in Pérez-Greaux's residence

was surely more easily accessible on the top shelf of a closet

than hidden underneath a bed or in the crawlspace of a ceiling.

And it is of no moment that Pérez-Greaux argues that the firearm

was unloaded since Grace also involved an unloaded firearm.                     See

 ("[A] gun does not even have to be operational, let

alone loaded, to qualify as a firearm for section 924 purposes.").

           Thus, viewing the evidence in the light most favorable

to the verdict, we conclude that based on the proximity of the

drugs,   accessibility       of   the    firearm,     and     the   surrounding

circumstances,     a    rational      factfinder      could     conclude       that


                                     - 44 -
Pérez-Greaux possessed the firearm "in furtherance of" the drug

trafficking crime and thus in violation of the § 924(c) charges.

                    2. Possession of a Machinegun in Furtherance of a
                    Drug Trafficking Crime

            In addition to challenging the "in furtherance" part of

his firearms convictions, Pérez-Greaux also contends that there is

insufficient evidence to conclude that he possessed a machinegun

in   furtherance     of    a    drug    trafficking       crime.       To    impose       an

additional    mandatory         minimum       sentence      of     thirty    years    for

possession    of     a     machinegun         under      § 924(c)(1)(B)(ii),          the

government must establish beyond a reasonable doubt that the

defendant (1) possessed a machinegun (2) in furtherance of (3) a

drug trafficking crime and, based on today's holding, (4) that the

defendant     knew       that     the     firearm      he        possessed    had     the

characteristics      that       brought    it    within      the    definition       of   a

machinegun.    § 924(c)(1)(B)(ii); see supra.                     Pérez-Greaux argues

that there is insufficient evidence to prove he knew the firearm

he possessed was a machinegun, while the government argues that,

notwithstanding that it did not set out to present mens rea

evidence about the type of firearm at trial (given that the

district    court    decided      that    a     mens   rea    instruction      was    not

appropriate), the evidence it did present was sufficient to prove

knowledge.     Viewing the evidence and all reasonable inferences

drawn therefrom in the light most favorable to the verdict, we



                                         - 45 -
conclude that there was sufficient evidence for a jury to establish

that Pérez-Greaux knew that the firearm he possessed had the

characteristics of a machinegun.           Thus, acquittal on this count is

not warranted.    We explain.

           "To meet the knowledge requirement threshold                      [under

§ 922(o)], the government must prove that 'the defendant had

knowledge of the characteristics that brought the gun within the

statutory definition, and not that []he had knowledge that the gun

was in fact considered a machine gun under federal law.'"                    United

States v. Torres-Pérez, 

 (1st Cir. 2021) (second

alteration in original) (quoting Nieves-Castaño, 480 F.3d at 599).

Further,   "[t]he      requisite    mens     rea    may   be    established     by

circumstantial evidence."          Id. at 32-33 (quoting Nieves-Castaño,

480 F.3d at 601).        And while "[i]ndividual pieces of evidence

viewed in isolation may be insufficient in themselves to prove a

point, . . . in     cumulation     [they]     may   indeed     meet   the    mark."

United States v. Shaw, 

 (1st Cir. 2012).                    Thus,

at the Rule 29 posture, the question before us is whether the

"evidence, including all plausible inferences drawn therefrom,

would allow a rational factfinder to conclude beyond a reasonable

doubt   that     the    defendant     committed       the      charged      crime."

Torres-Pérez, 

 (quoting United States v. Troy, 583

U.S. F.3d 20, 24 (1st Cir. 2009)).          We conclude that, in this case,

a rational factfinder could reach this conclusion.


                                     - 46 -
             Here, crediting the government's witnesses, as we must

on a Rule 29 motion, the cumulation of evidence reveals that the

firearm in question was indeed a machinegun as federal law defines

it and that a reasonable jury could draw the reasonable inference

that Pérez-Greaux knew it was one.             First, the government offered

testimony from a firearms expert that the firearm in question was

a semiautomatic Glock 26 pistol that had been converted into a

fully   automatic        machinegun   through     the    installation    of   an

automatic sear, created by an individual and not by Glock, on the

back of its slide.         The expert also testified that, based on his

training and expertise, he could simply look at the firearm and

conclude that it is a machinegun but that he confirmed this

conclusion by test firing the weapon.               While "a juror may not

reasonably infer merely from the fact that one constructively

possesse[d] a machinegun that the defendant knows . . . about the

characteristics of that weapon," United States v. Pina-Nieves, 

   (1st    Cir.   2023),   here,    the   jury   was   given   the

opportunity to view the machinegun and the visible alterations

made as described by the government's expert.                   Moreover, the

government     presented      evidence    that     Agent   Rivera     witnessed

Pérez-Greaux carrying a firearm in a holster on his hip, that

Pérez-Greaux stored the firearm in the same bag as a thirty-round

magazine, told the agents carrying out the search warrant where

the firearm was located, possessed firearm periodicals, and had an


                                      - 47 -
extended magazine.         From this evidence, a reasonable jury could

have inferred that the firearm Agent Rivera saw Pérez-Greaux

carrying was the same machinegun recovered by law enforcement,

meaning   Pérez-Greaux      had   "handled"     the   firearm.    Because     he

"handled" the firearm and was familiar with firearms -- inferred

from his possession of firearm periodicals -- a reasonable jury

could have thus concluded that he knew it had been altered to fire

automatically.

              This court has affirmed the denial of a Rule 29 motion

for acquittal on less evidence.          For instance, in Torres-Pérez, we

concluded that the defendant knew the firearm was a machinegun

where   the    defendant    was   seen   removing     the   firearm   from   the

waistband of his shorts and throwing it into a truck via the open

driver's side window.        

.        There, as here, the

government     presented    evidence     that   the   defendant   handled    the

weapon (when he threw it into a truck), as well as expert testimony

that the weapon's chip was visible just from looking at the

firearm, officer testimony that "he could tell by looking at the

Glock that [it] had been altered," evidence that the alterations

to the firearm were "obvious and visible," and evidence that the

defendant had "run from police," from which the jury could infer

"consciousness of guilt."         

.      Additionally, since "the

jury could view the Glock for themselves during trial and had the

opportunity to decide whether the chip was visible and obvious to


                                    - 48 -
[the defendant,]" the jury could infer that the defendant "knew

the Glock could fire multiple bullets with one pull of the trigger"

based on the "extended magazine."         

   As we have already

described, similar evidence was also presented at Pérez-Greaux's

trial.

          The government also presented evidence that:       (1) the

firearm was found in the same bag as a thirty-round magazine, from

which the jury could have drawn the inference that the firearm

could fire multiple bullets; (2) Pérez-Greaux possessed firearm

periodicals,    evincing   his     knowledge    of   firearms;   and

(3) Pérez-Greaux and the person who gave him the firearm, whether

crediting Pérez-Greaux's first or second version of how he came to

possess it, were close, such that they would have told him that

the firearm was a machinegun had he not in fact seen the weapon.

See Laureano-Pérez, 

 ("Given this apparent closeness,

a jury could rationally conclude that [the co-conspirator] would

have confided in [the defendant] regarding the [contents] of the

bag.").   Thus, we cannot say that, given the cumulation of all of

this circumstantial evidence, no levelheaded jury could have found

Pérez-Greaux guilty.   See Bobadilla-Pagán, 

.

          Pérez-Greaux counters that the government failed to

present sufficient evidence because it did not present evidence

that a layperson (rather than an expert) could draw the conclusion,

simply by looking at the firearm, that it had been modified to a


                                 - 49 -
machinegun.         But this argument is unavailing since such evidence

was not required in Torres-Pérez where we affirmed on similar

facts.        See 

.            He further argues, in a cursory

manner, that his facts are analogous to those in Nieves-Castaño,

where we reversed a conviction based on insufficient evidence of

knowledge.         See 480 F.3d at 600-02.          There, however, we considered

a rifle, not a Glock pistol, and the firearm had been modified via

an internal alteration, such that the only external evidence that

the firearm had been modified was a "small mark or hole" that was

not easily noticeable, and thus was unlike the visible alteration

present here.         Id. at 600.      Further, unlike here, no evidence was

presented      to    show    that    the    defendant    had   "any   expertise   in

firearms."         Id. at 601.      For all of these reasons, Pérez-Greaux is

not entitled to an acquittal on this count.

               C.    PRETRIAL AND TRIAL ERRORS

               Finally, Pérez-Greaux separately requests a new trial on

the basis that (1) the district court erred in three evidentiary

rulings, which denied him the right to a fair trial; (2) that

prosecutorial misconduct in closing arguments violated his Fifth

and Sixth Amendment rights; (3) that the district court erred in

denying his motion to suppress without a Franks hearing; and

(4) that, cumulatively, the errors already outlined undermined his

right    to    a    fair    trial.     We    address    each   argument   in   turn,




                                           - 50 -
ultimately concluding that a new trial is unnecessary based on

these purported errors.

                     1.    Evidentiary Rulings

              Pérez-Greaux first contends that the district court

erred in three evidentiary rulings, namely that the district court

(a) precluded            defense         witness       testimony;          (b) excluded

cross-examination of Agent Miranda on Pérez-Greaux's mens rea

statements; and (c) admitted images extracted from two phones in

Pérez-Greaux's house and opinion testimony that these materials

evidence specific prior illegal conduct.                        All asserted errors

having been preserved, we review for abuse of discretion, United

States   v.    Greaux-Gomez,           

   (1st   Cir.   2022),

affording the district court discretion so long as it did not make

an error of law, Koon v. United States, 

 (1996).

              a.    Preclusion of Testimony by DRNA Lieutenants

              Pérez-Greaux first argues that the district court erred

in preventing him from presenting testimony from three lieutenants

who   worked       for    the   Puerto      Rico    Natural    Resources    Department

("DRNA") on the Caño Tiburones Reserve near his residence.                           At

trial, the government offered testimony from Agent Rivera that he

had surveilled Pérez-Greaux's house from an empty lot belonging to

the DRNA and had seen Pérez-Greaux carrying a weapon on his hip.

              To    rebut       this     testimony,     Pérez-Greaux        sought    to

introduce the testimony of three lieutenants who would testify, in


                                            - 51 -
essence, that they were the only three lieutenants that were on

duty to oversee the reserve, that no one requested permission to

surveil Pérez-Greaux's residence from the reserve, and that even

if someone had requested permission, they would not have been able

to   grant   such     permission   because     they    were    not     the   agents

responsible for granting such requests. This testimony would show,

according to Pérez-Greaux, that Agent Rivera did not actually enter

the reserve to conduct surveillance, and consequently, could never

have seen Pérez-Greaux with a gun on his hip.                       The government

objected     to     this   testimony,       arguing    that     it     constituted

impeachment of a witness on a collateral matter via extrinsic

evidence prohibited by Federal Rule of Evidence 608(b).                         The

district     court    agreed   with   the    government       and    excluded   the

testimony, finding that the testimony offered would go to whether

or not Agent Rivera was in the lot, rather than whether he actually

(from some site) saw Pérez-Greaux with the firearm.                     On appeal,

Pérez-Greaux argues that the testimony was impermissibly excluded

as collateral.

             "A matter is collateral if 'the matter itself is not

relevant in the litigation to establish a fact of consequence,

i.e., not relevant for a purpose other than mere contradiction of

the in-court testimony of the witness.'"              Maldonado-Peña, 

-36 (quoting United States v. Marino, 

 (1st

Cir. 2002)).         We do not see how the district court abused its


                                      - 52 -
discretion in excluding this testimony. Testimony from these three

lieutenants would not be that they never saw Agent Rivera in the

lot or that Agent Rivera never saw Pérez-Greaux with a firearm.

Rather, said testimony would concern whether Agent Rivera had

entered the lot with or without permission, and no proffer was

made that the reserve could only be entered with permission. Given

this, we agree with the district court that such a matter was

collateral because it did not go directly to the issue of whether

Agent      Rivera    actually    saw     Pérez-Greaux    with   the   firearm.

"[W]hether a matter is collateral or material is within the

district court's discretion," 

 (citation omitted), and we

conclude that the district court did not abuse its discretion.10

             b.     Preclusion of Cross-Examination of ICE Agent Miranda

             Pérez-Greaux also argues that the district court abused

its   discretion       in   preventing    him   from   cross-examining   Agent

Miranda regarding the defendant's post-Miranda statement that he

"had no knowledge that the firearm had been modified to operate as

a fully automatic handgun."            We do not dive into this claim of

error because it goes directly to the mens rea count that we have

concluded must be vacated and remanded for a new trial, and the


      10Pérez-Greaux also argues that the district court violated
his due process right to "present a defense." However, not having
developed this argument, we deem it waived.     United States v.
Zannino, 

 (1st Cir. 1990) ("[I]ssues adverted to in
a perfunctory manner, unaccompanied by some effort at developed
argumentation, are deemed waived.").


                                       - 53 -
ruling will likely be reconsidered.      See United States v. Sasso,

 (1st Cir. 2012) (commenting that, because a new

trial was warranted for an erroneous jury instruction, the court

would not examine some alleged trial errors).

         c.     Admission of Prior Bad Acts Evidence

         Pérez-Greaux further argues that the district court

abused its discretion in its decision to admit into evidence

photographs of what appear to be bricks of cocaine, thousands of

dollars in cash, various money transfer receipts, USPS tracking

information, and a series of text messages, contending that the

images were propensity evidence that should have been excluded

under Federal Rule of Evidence 404(b) ("Rule 404(b)").

         Rule 404(b) governs the admissibility of evidence of

"crimes, wrongs, or acts" other than that for which the defendant

is on trial.    Fed. R. Evid. 404(b).    Generally, such evidence is

"not admissible to prove a person's character in order to show

that on a particular occasion the person acted in accordance with

the character."    

   This is known as the forbidden "propensity

inference."    See, e.g., United States v. Varoudakis, 

 (1st Cir. 2000).     However, exceptions exist.    If the evidence

is being offered for another purpose, such as to show "motive,

opportunity, intent, preparation, plan, knowledge," et cetera,

Fed. R. Evid. 404(b)(2), then such evidence is admissible if it

passes a two-step analysis, Varoudakis, 

.       "First,


                                - 54 -
the evidence must have 'special relevance' to an issue in the case

such as intent or knowledge, and must not include 'bad character

or propensity as a necessary link in the inferential chain.'"             

(quoting United States v. Frankhauser, 

 (1st Cir.

1996)).   Second, even if the evidence is "special[ly] relevant,"

 it may still be excluded under Federal Rule of Evidence 403

("Rule 403") "if its probative value is substantially outweighed

by the danger of," among other things, unfair prejudice.           Fed. R.

Evid. 403.       And "[i]n reviewing Rule 403 challenges, we are

extremely deferential to the district court's determination."

United States v. Otero-Méndez, 

 (1st Cir. 2001).

              Pérez-Greaux argues that the district court erred when

it   failed    to   engage   in    the   correct,   two-step   analysis   in

determining the admissibility of the photos.             While it is true

that the district court did not explicitly outline that it was

engaging in the two-step approach, the record reveals that the

court made the requisite considerations implicitly, and that is

enough.   See United States v. Breton, 

 (1st Cir.

2014) ("We give great deference to a district judge's balancing of

probative value versus unfair prejudice . . . .          This is true even

when a judge does not expressly explain the Rule 403 balancing

process on the record.").         First, when the government argued that

the evidence was admissible to show that Pérez-Greaux had possessed

the cocaine with the intent to distribute it, the district court


                                    - 55 -
agreed, noting that it would "at most" be evidence of "intent,

knowledge, [etc.]."    Second, the district court asked Pérez-Greaux

to focus his argument on issues of "prejudice, bad faith, [and any

other] evidentiary reason" to suppress the images.            (Emphasis

added).   Such a request indicates that the court was considering

step two (probative value and prejudice) in its assessment of the

issue, especially since we have repeatedly held that "the absence

of an express Rule 403 finding . . . does not mean the district

judge failed to perform this analysis."        Breton, 

;

see United States v. García-Sierra, 

 (1st Cir.

2021) (explaining that while the court failed to explicitly address

Rule 403 balancing, the record as a whole reveals that the court

engaged in the required analysis via its questioning of counsel).

          Even so, Pérez-Greaux argues that the images should not

have been admitted because he was prejudiced by the last-minute

disclosure of the images (the government moved to admit them the

day before trial).      The district court found that the delay in

disclosing the evidence was not prejudicial because Pérez-Greaux

could have requested a continuance and did not.       We find no fault

in the district court's logic and find no abuse of discretion by

admitting these images.

               2.     Prosecutorial Misconduct

          We   now    reach   Pérez-Greaux's     contention   that   the

government made improper remarks at two parts of its closing


                                - 56 -
argument, which he implies poisoned the well and affected the

trial's    outcome.      We    review    preserved   challenges       to   closing

arguments de novo and unpreserved challenges for plain error.

United States v. González-Perez, 

, 19 (1st Cir. 2015).

Statements are harmful if they "so poisoned the well that the

trial's outcome was likely affected, thus warranting a new trial."

Id. (quoting United States v. Rodríguez, 

 (1st Cir.

2015)).    Ultimately, we disagree with Pérez-Greaux's arguments for

the reasons set forth below.

            First, Pérez-Greaux takes issue with the government's

emphasis on Agent Rivera's supposed description of the black

firearm he saw on Pérez-Greaux's hip as "match[ing] the black

pistol that was found in the closet" days later when officers

executed    the    search     warrant.     The    district    court    overruled

Pérez-Greaux's objection that this was a misstatement of the

evidence.    Properly preserved, we review this challenge de novo.

See 

            On    appeal,      Pérez-Greaux      focuses     his   argument     on

allegations that Agent Rivera was not truthful in his testimony

about seeing a gun on Pérez-Greaux's hip, and we understand his

argument    to    be   that   the   government     improperly      carried    this

misstatement forward into its closing argument to the jury.                  While

our review of the record demonstrates that Agent Rivera did not

specifically state that the firearm "matched" the weapon seized,


                                     - 57 -
as the government stated in its closing, he did say that the

firearm looked similar to his own Glock pistol and that it was

indeed a Glock-brand machinegun that was eventually found.            Taking

context into account, it appears that in making its closing

argument, the government was inviting the jury to infer that the

firearm Agent Rivera says he observed matched the firearm found in

the children's bedroom.        While prosecutors cannot refer to facts

not in evidence during closing remarks, they can ask the jury to

draw reasonable inferences.         United States v. Ponzo, 

 (1st Cir. 2017).     And this inference was reasonable given the

brand of the firearm       recovered and its resemblance to Agent

Rivera's personal weapon.           As such, we cannot say that this

statement     was   improper   or    that    the   prosecutor    engaged   in

misconduct.    See González-Perez, 

.

            Moving on to his second complaint about the government's

closing statement, Pérez-Greaux contends that the government also

"misstated both the law and the facts and implied special knowledge

amounting to personal testimony" when the prosecutor stated to the

jury in rebuttal that "[d]rugs and a gun go like rice and beans,

'co[mo] arroz y habichuelas.'11         They go together.       That gun was

there to protect the drugs," in attempting to make the case that

the firearm was used "in furtherance of" the drug trafficking


     11"Como arroz y habichuelas," is Spanish for "like rice and
beans," which the government translated for the jury.


                                    - 58 -
crime. Perez-Greaux did not object to this statement, so we review

for plain error.          On plain error review, Pérez-Greaux "must show

that '(1) an error occurred (2) which was clear or obvious and

which not only (3) affected the defendant's substantial rights,

but also (4) seriously impaired the fairness, integrity, or public

reputation of the proceedings.'"                 United States v. Spencer, 

 (1st Cir. 2017) (alteration omitted) (quoting United

States     v.     Kasenge,    

   (1st   Cir.     2011)).

Pérez-Greaux, however, fails to address the four prongs of plain

error in his opening brief, so we deem his argument waived and say

no more about it.12        See United States v. Espinoza-Roque, 

, 36 (1st Cir. 2022) (explaining that the appellant waived a

"claim on appeal by failing to address the governing standard of

plain error review in his opening brief").

                    3.    Franks Hearing

             We    next    turn   to   Pérez-Greaux's        contention    that   the

district court erred in denying him a Franks hearing.                      Under the

Supreme Court's decision in Franks v. Delaware, 

(1978), a defendant may obtain an evidentiary hearing "to challenge

the truthfulness of statements made by law enforcement agents in

a   search      warrant    affidavit"         should   the   defendant     make   "'a



       Even if we were to look beyond Pérez-Greaux's opening brief
      12

and turn to his reply brief, there too he fails to develop his
argument for plain error since he acknowledges the standard but
fails to address the four prongs.


                                        - 59 -
substantial preliminary showing' that: 1) the warrant affidavit

contains a false statement made 'knowingly and intentionally, or

with reckless disregard for the truth' and 2) that 'the allegedly

false statement was necessary to the finding of probable cause.'"

United States v. Hicks, 

 (1st Cir. 2009) (quoting

Franks, 

).      We review a district court's denial

of a request for a Franks hearing for clear error.         United States

v. Austin, 

 (1st Cir. 2021) (citing United States

v. Graf, 

 (1st Cir. 2015)).      "[W]hen we are left with

the   definite   and   firm   conviction   that   a   mistake   has   been

committed," clear error exists.        Graf, 

 (quoting

Hicks, 

).

           On appeal, Pérez-Greaux maintains, as he did below,13

that he was entitled to a Franks hearing because the statement

made by Agent Rivera in support of the search warrant -- that on

June 1, 2018, he saw Pérez-Greaux leave his residence with a pistol


      13Pérez-Greaux filed a motion to suppress the evidence
obtained from the search of his residence on the sole basis that
Agent Rivera's affidavit supporting the search warrant application
included a false statement -- that of Agent Rivera observing
Pérez-Greaux with a firearm on his hip -- and that without this
statement the affidavit did not establish the requisite probable
cause for the issuance of the search warrant.       Pérez-Greaux's
motion included a request for a Franks hearing. As the parties
know well, the court initially scheduled a Franks hearing,
continued the hearing date a few times, and ultimately vacated the
hearing date over Pérez-Greaux's objection.    The district court
denied the motion to suppress, adopting (over Pérez-Greaux's
objection) a magistrate judge's report and recommendation that
Pérez-Greaux was not entitled to a Franks hearing.


                                 - 60 -
on his hip -- was false and, absent this statement, Agent Rivera's

affidavit provided insufficient probable cause to issue a search

warrant.     In support of this Franks hearing motion, Pérez-Greaux

supplied nothing beyond his own affidavit stating that, from

May 29, 2018 to June 5, 2018, he had "never been outside [his]

residence with any type of firearm."14            The magistrate judge found

that    Pérez-Greaux    "failed   to   make   a     substantial   preliminary

showing that he was entitled to a Franks Hearing" because he only

attacked one of the factual bases within Agent Rivera's affidavit

and failed to meet his burden to show the stated observation was

false.      He did not provide any indication that the information

from the confidential informant, upon which Agent Rivera was

relying, was false or unreliable in any way or show that the

information     was     immaterial.      The       district   court       denied

Pérez-Greaux's motion to suppress, finding the magistrate judge's

recommendation        "well-supported"      and     concluding     that     the

information      from     the     confidential        informant -- on       its



        Pérez-Greaux belatedly submitted additional evidence for
       14

the court's consideration when he objected to the magistrate
judge's report and recommendation, including (1) a logbook from
the security company for the residential development (in which
Agent Rivera averred he had observed Pérez-Greaux) purporting to
show the absence of an entry for law enforcement on June 1, 2018,
and (2) an affidavit from an investigator who had interviewed a
security guard for the residential development, stating that the
security guard did not recall law enforcement's presence at the
development on June 1, 2018. The district court concluded that
the evidence was "insufficient to vitiate the probable cause
underlying the search warrant."


                                   - 61 -
own -- "establishe[d] probable cause for the search warrant."

After reviewing the record, we cannot conclude that this decision

was wrong.         See Graf, 

.

              We begin our discussion with the first prong of the

"substantial         preliminary    showing"        test:    that    the    "warrant

affidavit contains a false statement."                 Hicks, 

.

While Pérez-Greaux's sworn statement challenges the truthfulness

of Agent Rivera's statement about what he purportedly observed,

"[n]ot every challenge to an affiant's veracity will lead to an

evidentiary hearing."          United States v. Southard, 

(1st   Cir.    1983).        "To   mandate    an     evidentiary     hearing,    the

challenger's attack must be more than conclusory and must be

supported by more than a mere desire to cross-examine.                     There must

be allegations of deliberate falsehood or of reckless disregard

for the truth, and those allegations must be accompanied by an

offer of proof."            

 (quoting Franks, 

).

Pérez-Greaux's statement that he was not outside of his residence

with any type of firearm during the relevant period amounts to

what we have described in the past as a conclusory assertion.                      It

also neither illustrates that Agent Rivera acted "knowingly and

intentionally, [n]or with reckless disregard for the truth," as

required by Franks.         

.

              We     have   previously       held     that    flat    denials     of

allegations, like Pérez-Greaux's, fall short of the "substantial


                                      - 62 -
preliminary showing" required to justify a Franks hearing because

this only "set[s] up a swearing contest" -- one side has to be

lying -- but    a     flat      denial    alone   "do[es]   not    demonstrate    a

substantial possibility of affiant perjury."                Southard, 

   (holding    bare      denials     of   the   facts     stated    in   law

enforcement's       affidavit       "do    not    demonstrate     a     substantial

possibility of affiant perjury" and therefore did not help the

defendants     meet       the    "substantial       preliminary       showing"    of

falsehood).     We have also held that a defendant was unsuccessful

in discrediting the affidavit made in support of a warrant to

search his residence -- which had been based on a detective's

statements that a confidential informant had purchased drugs from

the   defendant     and      that   the    police   department        had   observed

controlled buys, including one within 72 hours -- because the

defendant's own statement that he had not sold drugs to anyone in

the past 72 hours could not fill the "factual gap in [his] attempt

to show the affidavit's inaccuracy -- and thus its knowing or

reckless falsity."         United States v. Moon, 

(1st Cir. 2015).

            Even if we, like the district court, consider the two

exhibits first submitted to the court when Pérez-Greaux objected

to the magistrate judge's report and recommendation, see supra

note 14, we are still not persuaded that the district court clearly

erred by concluding Pérez-Greaux failed to show Agent Rivera made


                                         - 63 -
a false statement.       The exhibits purport to show that Agent Rivera

was lying because the security guard on duty at the time did not

record or recall law enforcement entering the neighborhood on

June 1, 2018.       But the warrant affidavit indicates that, the two

times Agent Rivera surveilled Pérez-Greaux's residence, he was in

an    unmarked    car   with    tinted   windows.        Further,      there   is   no

indication       from   the    proffered   exhibits      that    law    enforcement

announced or were required to announce its presence to the security

guards each time they entered the neighborhood.                  These exhibits,

therefore, do not help Pérez-Greaux show Agent Rivera lied about

seeing him with a firearm on June 1, 2018.                 See Moon, 

 (records from the American Automobile Association allegedly

showing that the defendant was out of town during at least one of

the    controlled       buys    were     insufficient       to   "discredit         the

affidavit's report of the controlled buys" because, at most, the

records showed that the defendant was out of town for only part of

the time period at issue).

            Because      Pérez-Greaux      has    not    made    a     "substantial

preliminary       showing"     that    Agent    Rivera's    "warrant      affidavit

contain[ed] a false statement," we need not discuss the test's

second    prong -- whether       he    showed    "that   'the    allegedly     false




                                       - 64 -
statement was necessary to the finding of probable cause.'"15

Hicks, 

 (quoting Franks, 

).                     We

thus conclude that the district court was not clearly wrong to

deny the Franks hearing.16

III. Conclusion

           For     the       reasons     set    forth   above,          we   affirm

Pérez-Greaux's conviction as to Count One (possession of a firearm

in   furtherance   of    a    drug     trafficking   crime)       but   vacate   his

conviction   as    to    Count   Two     (possession    of    a    machinegun    in




      15 Pérez-Greaux invites us to consider the probable cause
prong of the "substantial preliminary showing" test de novo, while
the government argues, after acknowledging some contradictory case
law on this point, that said prong should be reviewed for clear
error. We leave this discussion for another day because we need
not reach the second prong, pertaining to probable cause, in this
case.
      16 Pérez-Greaux's last claim is that the cumulative effect of

all his asserted errors (the evidentiary rulings, inadequate jury
instruction, and prosecutorial misconduct) undermined his right to
a fair trial and warranted reversal of his convictions. Cumulative
error exists where "a column of errors may [] have a logarithmic
effect, producing a total impact greater than the arithmetic sum
of its constituent parts" "even though the same compendium of
errors, considered one by one, would not justify such relief."
United States v. Padilla-Galarza, 

 (1st Cir. 2021)
(alteration in original) (quoting United States v. Sepulveda, 

 (1st Cir. 1993)). With respect to the count of
conviction for possession of a firearm in furtherance of a drug
trafficking crime, Pérez-Greaux's claim of cumulative error goes
nowhere because we have not found any errors making this count of
conviction reversible. See Maldonado-Peña, 

. As to
the count of conviction for possession of a machinegun in
furtherance of a drug trafficking crime, we need not address the
"cumulative error" claim because we agree with Pérez-Greaux's
asserted instructional error, vacate his conviction, and remand
for a new trial on this count.


                                       - 65 -
furtherance of a drug trafficking crime) and remand for a new trial

as to Count Two.




                              - 66 -