UNITED STATES DISTRICT COURT FOR THE DISTRICT OF NEW HAMPSHIRE

United States of America

v. Crim. No. 20-cr-081-01-LM Opinion No.

P Lester Aceituno

ORDER

Defendant Lester Aceituno is charged in an indictment with one count of

conspiracy to commit bank fraud in violation of

and two counts of

aggravated identity theft in violation of 18 U.S.C. § 1028A. Before the court is

Aceituno’s motion in limine to exclude the testimony of the government’s fingerprint

expert. See doc. no. 94. The court held an evidentiary hearing on the motion, at

which both parties presented expert witnesses. The government’s expert testified to

her fingerprint identification procedures as well as her conclusion that the latent

fingerprint is a match for Aceituno’s known print. The defense expert opined that

the methodology and standards the government’s expert used were too vague to be

reliable, and that errors in her analytical process cast further doubt on the

identification. By endorsed order dated October 5, 2023, the court denied Aceituno’s

motion and indicated that a written order would follow.

LEGAL STANDARDS

Federal Rule of Evidence 702 provides the requirements for expert

witness testimony: A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: (a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case.

Based on these requirements, an expert witness's testimony may be

challenged on the grounds that the witness is not qualified to give the opinion, the

opinion is not based on specialized knowledge, the opinion is not reliable, or the

opinion is not relevant. Carrozza v. CVS Pharm., Inc.,

(1st Cir.

2021); Bogosian v. Mercedes-Benz of N. Am.,

(1st Cir. 1997). The

proponent of the expert witness bears the burden of showing by a preponderance of

evidence that the testimony is admissible. See Martínez v. United States,

(1st Cir. 2022); United States v. Tetioukhine,

(1st Cir. 2013);

see also Fed. R. Evid. 702 advisory committee's note to 2023 amendment (explaining

that 2023 changes “clarify and emphasize” that the preponderance of the evidence

standard applies under Rule 702).

The judge has a gatekeeping role to ensure that an expert witness's

testimony is both reliable and relevant. Martínez,

. In carrying out

that function, the judge focuses on the process that generated the opinion, not on

the opinion itself. López-Ramírez v. Toledo-González,

, 94 (1st Cir. 2022)

(citing Daubert v. Merrell Dow Pharms., Inc.,

(1993)). “There is

an important difference between what is unreliable support and what a trier of fact 2 may conclude is insufficient support for an expert's conclusion.” Milward v. Acuity

Specialty Prods. Grp., Inc.,

, 15 (1st Cir. 2011); López-Ramírez, 32 F.4th

at 94. “Vigorous cross-examination, presentation of contrary evidence, and careful

instruction on the burden of proof are the traditional and appropriate means of

attacking shaky but admissible evidence.” Daubert,

.

After Daubert established the trial court’s gatekeeping function with respect

to scientific expertise, the Supreme Court clarified in Kumho Tire Co. v.

Carmichael,

(1999), that this function also extended to “technical”

or “other specialized knowledge.” E.g., Lawes v. CSA Architects & Eng’rs LLP,

, 98 n.39 (1st Cir. 2020). In Kumho Tire, the Court upheld the trial court’s

decision that an expert in engineering lacked “sufficient specialized knowledge to

assist the jurors ‘in deciding the particular issues in the case.’” Kumho Tire,

, 158 (quoting 4 J. McLauglin, Weinstein’s Federal Evidence ¶ 702.05[1],

at 702-33 (2d ed. 1998)). Following Kumho Tire, the key issue for non-scientific

testimony is “whether the expert ‘employs in the courtroom the same level of

intellectual rigor that characterizes the practice of an expert in the relevant field.’”

United States v. Monteiro,

(D. Mass. 2006) (quoting

Kumho Tire,

).

Regardless of whether the testimony is scientific, technical, or specialized, a

court must determine whether the proffered expert testimony is sufficiently

reliable.

(citing Kumho Tire,

). In making that determination, the

court must assess the reliability of the methodology underlying the expert’s

3 testimony.

Daubert outlines five factors that should guide courts in making this

reliability determination: (1) whether the methodology can be or has been tested; (2)

whether the methodology has been subjected to peer review and publication; (3) the

known or potential error rate;1 (4) the existence of standards controlling the

methodology’s operation;2 and (5) the degree to which the methodology has been

accepted within the relevant discipline. Daubert,

. However, the

Daubert factors “may not perfectly fit every type of expert testimony, particularly

technical testimony based primarily on the training and experience of the expert.”

Monteiro,

. Thus, the court may also look to other factors in

determining whether a methodology is sufficiently reliable. See, e.g., Kumho Tire,

(emphasizing that the Daubert factors are neither definitive nor

exhaustive); United States v. Mitchell,

(3d Cir. 2004) (quoting In

re Paoli R.R. Yard PCB Litig.,

, 742 n.8 (3d Cir. 1994)) (listing additional

factors used to determine a method’s reliability).

1 The advisory committee’s notes to the 2023 amendments to Rule 702 acknowledge that a known error rate is preferable but may not always be available. “In deciding whether to admit forensic expert testimony, the judge should (where possible) receive an estimate of the known or potential rate of error of the methodology employed, based (where appropriate) on studies that reflect how often the method produces accurate results.” Fed. R. Evid. 702 advisory committee’s note to 2023 amendments.

2 The advisory committee’s notes to the 2023 amendments also make clear that

where the methodology involves subjective assessments, the expert should avoid statements of certainty: “Forensic experts should avoid assertions of absolute or one hundred percent certainty—or to a reasonable degree of scientific certainty—if the methodology is subjective and thus potentially subject to error.” 4 If the court determines that the methodology is reliable, it must then decide

whether the expert reliably applied the methodology to the facts of the case. Fed. R.

Evid. 702(d); Monteiro,

. Expert testimony regarding the

comparison of features, such as the ridges in fingerprints, “must be limited to those

inferences that can reasonably be drawn from a reliable application of the principles

and methods.”3 Fed. R. Evid. 702 advisory committee’s note to 2023 amendments.

The court must remain mindful that it is a “gatekeeper,” not an “armed guard,” and

the “party who proffers expert testimony” need not prove to the court “that the

expert's assessment of the situation is correct.” Ruiz-Troche v. Pepsi Cola of P.R.

Bottling Co.,

(1st Cir. 1998). “[O]nce a trial judge determines the

reliability of the proffered expert's methodology and the validity of his reasoning,

the expert should be permitted to testify as to the inferences and conclusions he

draws from it, and any flaws in his opinion may be exposed through cross-

examination or competing expert testimony.” United States v. Mooney,

(1st Cir. 2002).

3 Effective December 1, 2023, the language of Rule 702(d) will state: “the

expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.” Fed. R. Evid. 702(d) 2023 amendment. This change does not impose “any new, specific procedures,” but instead emphasizes the bounds of the inferences permitted in expert testimony. Fed. R. Evid. 702 advisory committee’s note to 2023 amendments. 5 BACKGROUND

I. Factual and Procedural Background

The indictment alleges that Aceituno entered into a conspiracy to deposit and

withdraw funds from fraudulently obtained checks and money orders. Specifically,

it alleges that, between June 1, 2016, and October 10, 2017, the conspirators opened

accounts with two different banks using other individuals’ identification

information. The conspirators allegedly deposited checks into these accounts and

then obtained the funds through debit card purchases, withdrawals, money orders,

and cashier’s checks. Doc. no. 2 at 2. The indictment also alleges that, in relation to

this conspiracy, Aceituno knowingly possessed and used the names, dates of birth,

and Social Security numbers of two other people. Id. at 4.

In 2017, the government located a fingerprint on a post office box application

written in the name of a victim in this case.4 The government intends to argue that

the fingerprint is a match for one of Aceituno’s known prints. To that end, the

government intends to present the testimony of Patricia Cornell, a fingerprint

analyst for the U.S. Postal Inspection Service’s National Forensic Laboratory, as an

expert in latent fingerprint analysis. In 2017, Cornell analyzed the latent print

found on the application and identified it as a match with a known print of

Aceituno’s. She will testify at trial that she used an identification method called

“ACE-V,” which stands for Analysis, Comparison, Evaluation, and Verification.

4 The unidentified fingerprint is referred to as a “latent” print, while fingerprints already identified to a particular individual are referred to as “known” fingerprints. 6 Nat’l Rsch. Council, Strengthening Forensic Science in the United States: A Path

Forward 137 (2009).

“ACE-V” is an acronym that describes a four-part process. “A” stands for

“analysis.” The expert analyzes the latent fingerprint to determine whether the

features are sufficiently detailed and clear for comparison. “C” stands for

“comparison.” The expert compares the levels of detail in the latent print to a

known fingerprint. “E” stands for “evaluation.” The expert evaluates the matching

features between the two prints to determine whether there is a match. “V” stands

for “verification.” During this last step, the result is verified. Id. at 137-38. Cornell

followed these four steps. She is expected to testify at trial that, using the ACE-V

method, she identified the latent fingerprint as a match for Aceituno’s known print.

Aceituno moved to exclude Cornell’s testimony, arguing that the government

could not demonstrate that her testimony is admissible pursuant to Rule 702,

Daubert, and its progeny. He attached a report to his motion authored by Michele

Triplett, who, like Cornell, has extensive experience conducting fingerprint

identification analyses (doc. no. 94-2). Triplett opined that the government had

provided insufficient information regarding the criteria guiding Cornell’s analysis,

and that, based on the information that had been made available to her, she was

unable to conclude that Cornell’s identification was reliable. The government filed

7 an objection to Aceituno’s motion, and the court held an evidentiary hearing on

September 25, 2023, at which both Cornell and Triplett testified.5

II. The Government’s Expert

Cornell, a Senior Latent Fingerprint Examiner for the Postal Inspection

Service, testified at the hearing about her qualifications; her agency’s standards

and protocols; her use of the ACE-V method; and the application of ACE-V to the

fingerprints in this case. Cornell began by describing her qualifications. She worked

for four years as a basic fingerprint analyst before her promotion to her current

senior position. She held previous positions in law enforcement in which she

processed evidence from crime scenes, and taught classes on crime scene processing

as an adjunct professor. Cornell testified that she has more than 375 hours of

training in latent fingerprint identification. She has been certified by an

international accrediting body since 2009. Cornell’s position at the Postal Inspection

Service requires her to undergo proficiency testing every year and she has passed

every proficiency test. Cornell testified that she has identified more than 1,700

latent fingerprints that were of value for further study in 2023 alone.

In her testimony, Cornell described the Postal Inspection Service’s Standard

Operating Procedures (“SOPs”), which were also referenced in her expert report.

The SOPs instruct an analyst to utilize ACE-V, consider certain contextual factors

surrounding a print, look for increasing levels of detail, and make notations to

5 Per Aceituno’s request, the court permitted Triplett to testify via video due to

her schedule. While the government saw no need for a hearing, the government did not object to Triplett testifying via video in the event of such a hearing. 8 indicate different patterns or results. Cornell described the three levels of detail the

SOPs require examiners to consider. Level 1 detail includes the overall pattern on a

fingerprint, which may be an arch, a loop, or a “whorl.” Level 2 detail includes the

movement of ridges across a fingerprint, such as one ridge splitting into two. Level

3 detail consists of the minute details within a ridge, such as its shape, pores, and

edges. Cornell also testified that she compared the distance between and position of

features in a fingerprint.

Cornell then described each step in her application of ACE-V in this case with

an accompanying PowerPoint of colorful dots, which demarcated the marks she

made on an image of the latent fingerprint. First, in the “A” analysis stage, Cornell

testified that she looked at a photograph of the fingerprint and “instantaneously”

identified Level 1 detail: a left-slant loop. This meant that the fingerprint was likely

from the left hand. She identified the left-slant loop based on the overall shape of

the ridges. She then testified to the Level 2 detail, which she marked on the photo

with a sharp stylus called a “pointer.” The sharp point on the pointer left a distinct

mark on the image to document a unique feature, such as a ridge on the fingerprint.

Cornell explained that the pointer does not penetrate the image and does not in any

way “distort” that feature on the image.6 Once she found enough features on the

latent print that—in her view—made the print valuable for further identification,

she drew a red arch over the top of the image of the fingerprint as the SOPs

6 The court understood her testimony to be describing the marks as indentations, similar to braille. 9 required. She also marked and disregarded a section of the print that she thought

was too distorted to be reliable.

In the “C” comparison stage, Cornell testified that she compared the print to

the known prints of (1) an alleged co-conspirator in this case and (2) a postal

inspector assigned to this matter. Cornell found that neither matched. She then put

an unmarked image of the latent fingerprint into an online automated fingerprint

identification system (“AFIS”) database.7 Using an algorithm, the AFIS returns

potential matches based on the image submitted. Cornell testified that she ran the

image through the computer program and gave it a feature descriptor of a “left-

slant loop.” The AFIS returned an additional twenty known prints to compare,

including Aceituno’s. Through a process of elimination, she narrowed down the

candidates to Aceituno, and then to one of the ten prints on Aceituno’s fingerprint

card. Cornell testified that throughout the process she knew nothing about the case

except Aceituno’s name on his fingerprint card. She did not know that Aceituno was

a suspect in the case.

In conducting her comparison, Cornell testified that she compared the latent

print to Aceituno’s known print side-by-side. She used her pointer to mark features

that seemed to match on both the latent and known prints. She testified that she

found more data points in the known print to supplement her points on the latent

print. Cornell explained that she reached a preliminary conclusion that she had a

match. She then attempted to disprove her conclusion by looking for discrepancies

7 Aceituno does not challenge the government’s use of the AFIS.

10 in the marked points. The SOPs did not require Cornell to find a minimum number

of points to make her conclusion. She testified that she marked eleven features in

agreement between the two prints.

During the “E” evaluation stage, Cornell testified that she reviewed the

points in agreement between the two prints and preliminarily identified the latent

print to Aceituno. She formalized her opinion and documented it as a preliminary

identification. Cornell testified that this preliminary conclusion does not become a

full identification until it is verified.

For the “V” verification stage, Cornell sent the photograph of the latent

fingerprint and the known fingerprint card to another examiner: a peer at the

Postal Inspection Service. Cornell explained that her agency did not conduct blind

verifications. She referred to research showing that blind verifications take eight

times longer than unblind verifications, with a negligible impact on the verifier’s

conclusion.8 Here, the verifying peer knew before her verification that Cornell had

identified the latent fingerprint to a specific known print belonging to Aceituno. The

peer did not have Cornell’s documentation or marked points. Cornell’s verifying

peer repeated the comparison and evaluation stages of ACE-V, double-checking

Cornell’s work, and concluded, as did Cornell, that there was a match.

8 A “blind” verification occurs when the verifying peer repeats the original

examiner’s process without knowing the original examiner’s results. See United States v. Mahone,

(1st Cir. 2006) (referring to a blind verification where the verifier “had not reviewed [the initial] report before conducting his examination”).

11 Cornell testified that in July 2023, at the prosecutor’s request, she redid the

comparison, evaluation, and verification stages of ACE-V, with a blind verification.

During her second ACE-V procedure, Cornell again reached the conclusion that the

latent was a match for Aceituno’s known print. However, Cornell admitted that,

during her second ACE-V procedure, she marked one of the features by mistake.

Specifically, one point she marked on the latent print did not match the point she

marked on the known print. The verifying peer also marked one point in error.

Cornell testified that she discovered these mistakes after reading Triplett’s report.

Cornell explained that she corrected both mistakes by removing the errant marks

and identifying the features properly.

On cross-examination, Cornell was asked about the error rate for fingerprint

identification. She testified that she only knew of a potential false positive error

rate, which was 0.2%. Cornell was also asked about marked points on the latent and

known prints that seemed mismatched. She opined that, because a fingerprint may

be slightly distorted or smudged, otherwise identical ridges can appear to have

minor discrepancies. She characterized these discrepancies as “within tolerance,”

making them usable points.

III. The Defense’s Expert

In response to Cornell’s testimony, Aceituno called Michele Triplett. Triplett

testified to her criticisms of ACE-V generally and critiqued the application of ACE-V

in this case. Triplett acknowledged ACE-V’s wide acceptance, but she explained that

ACE-V is not a scientific method. Rather, in her view, ACE-V is no more than an

12 order of events or broad outline within which the agency or investigator operates.

The agency fills in the outline with standard operating procedures, or “SOPs.”

Triplett testified that she published a paper advocating for the field’s departure

from ACE-V. Although she was not opposed to an analyst using ACE-V, Triplett

opined that more specific information and protocols were needed.

With respect to the Postal Inspection Service’s SOPs—the specific procedures

Cornell used to implement ACE-V in this case—Triplett testified that the

documentation required by the SOPs was insufficient to evaluate Cornell’s work.

She opined that the lack of objective criteria set forth within the SOPs for matching

a latent print to a known print made it difficult to assess the reliability of Cornell’s

identification. Triplett also thought that the determination of a point as “within

tolerance” was a subjective, standardless judgment call, which further hurt the

reliability of the identification. Moreover, although Cornell testified that the print

in this case was “not complex,” Triplett disagreed. Triplett described the latent

print as complex, which would require “additional explanation, additional

documentation, [and] additional quality assurance measures.”

In addition, Triplett pointed out the two errors made in marking features. To

Triplett, these errors undermined Cornell’s entire identification. She testified that

there were other errors beyond those she identified in her expert report. Although

Triplett found fingerprints “extremely reliable” in most cases, she testified that the

procedures used in this case did not reliably support Cornell’s conclusion.

13 More broadly, Triplett testified to the error rates in fingerprint identification.

She testified that one of the first studies that provided an error rate showed that

identifications were correct in 99.8% of identifications, as Cornell testified. But

given the volume of fingerprint identifications and the variable print quality—

ranging from the simple to the more complex—Triplett testified that the studies do

not necessarily account for complex prints. Triplett testified that a study with more

complex latent fingerprints would show a higher error rate. The studies did not

disclose the complexity of the prints used and there was, in her words, “really no

rating mechanism.”

DISCUSSION

In his motion in limine, Aceituno argues that Cornell’s methodology—the

ACE-V method in combination with the Postal Inspection Service’s SOPs—is not

sufficiently reliable. Doc. no. 94 at 5. He also argues that Cornell did not reliably

apply this methodology.

The court will first analyze the reliability of the ACE-V

method used here, then consider whether Cornell’s application of this method was

sufficiently reliable.

I. The Government Expert’s Methodology Was Reliable

Aceituno first argues that Cornell’s ACE-V methodology was unreliable as

there is no way to reproduce her results under the SOPs she used because they are

not specific enough. The court analyzes the reliability of Cornell’s approach using

the relevant Daubert/Kumho factors.

14 A. Testability

Under Daubert and its progeny, the court may consider whether the method,

and its underlying premises, are testable. Daubert,

; Mitchell,

. “‘Testability’ has also been described as ‘falsifiability,’” which is the

ability to prove a hypothesis false. Mitchell,

.

Cornell testified that, during the comparison stage, she tested her

preliminary conclusions about the potential identification. Cornell attempted to

falsify her initial hypothesis that the latent print matched Aceituno’s known print.

She examined the eleven marked points on each of the prints, searching for

discrepancies between the points of identification. Cornell testified that, in her

view, she had sufficient information to test her hypothesis. She testified that she

also had a peer redo the comparison, evaluation, and verification to further test her

preliminary conclusion. The ACE-V process was repeated once more at the request

of the prosecution when Triplett identified Cornell’s error, essentially re-testing the

original conclusions. Although she marked one of those points in error, Cornell was

nonetheless able to reach the same conclusion, this time with a blind verification. In

light of the peer review and blind verification, as well as Cornell’s attempts to

falsify her conclusions, this factor cuts in favor of admitting Cornell’s testimony.

B. Peer Review and Publication

Both Cornell and Triplett testified that fingerprint identification has been

peer reviewed and published in scholarly journals. Cornell also testified that the

verification in the ACE-V method used at the Postal Inspection Service is itself a

15 form of case-by-case “peer review.” In other words, within each ACE-V fingerprint

identification, a peer at the Postal Inspection Service reviews the original analyst’s

evaluation. This layer of review adds to the reliability of ACE-V, and therefore

supports admission of Cornell’s testimony.

C. Known or Potential Error Rate

Neither expert could provide a definitive error rate for fingerprint

identification using the ACE-V method. Cornell testified that a “majority” of studies

found a false positive rate of 0.2%, and Triplett testified that she was aware of that

figure. But Triplett pointed out that most studies do not distinguish between error

rates where the expert is looking at simple versus complex latent prints.9 This is

important, according to Triplett, because the higher the complexity of the latent

print, the greater the error rate.

To Triplett, the latent print in this case was complex and therefore more

likely to be erroneously matched to a known print. But to Cornell, the print was

“not complex” and had only two minor errors. This dispute between experts over the

relative complexity of the latent print and the errors in the expert’s work is the kind

of debate that a jury should be allowed to hear and assess. See Mooney,

. However, the lack of a known error rate cuts against the reliability of Cornell’s

particular version of the ACE-V method.

9 Neither party submitted any of these studies in evidence.

16 D. Existence of Controlling Standards

Regarding the standards governing the ACE-V method, Aceituno argued at

the evidentiary hearing that the standards for documentation, specificity, and

quantitative detail were lacking. Cornell testified that she used ACE-V and her

agency’s SOPs to identify Aceituno’s fingerprint. Triplett opined that an agency’s

standards matter more than adherence to ACE-V’s four-step methodology, and she

expressed reservations about the lack of quantitative standards in the SOPs used in

this case.

The court agrees with Triplett’s characterization of the ACE-V method. An

acronym of four letters does not create a technical methodology. By itself, ACE-V is

a mere organizational structure, comparable to the “IRAC” (“Issue, Rule,

Application, Conclusion”) writing structure that law students learn in first-year

legal writing courses. Just because a lawyer uses the IRAC method to write a brief

does not render the brief more likely to reach either a reliable or correct legal

conclusion. Likewise, ACE-V is only as reliable as the testing and analysis that

takes place within it.

The Postal Inspection Service’s SOPs neither set thresholds for the number of

features an analyst should identify nor provide metrics to determine whether the

features between two prints sufficiently correspond. Triplett conceded, however,

that requiring a minimum number of features to find a match would not necessarily

improve the accuracy of the identification. The SOPs require that analysts make

certain notations to indicate their findings on the fingerprint photographs and

Cornell testified about these details. Cornell’s testimony supplemented and 17 explained in detail the operation of the SOPs within each step of the procedure. The

court finds that this factor cuts slightly in favor of admitting Cornell’s testimony.

E. Acceptance Within the Relevant Discipline

Widespread acceptance in the relevant discipline “can be an important factor

in ruling particular evidence admissible, and ‘a known technique which has been

able to attract only minimal support within the community’ may properly be viewed

with skepticism.’” Daubert,

(quoting United States v. Downing,

(3d Cir. 1985)).

At the evidentiary hearing, both experts testified to the long-standing use of

the ACE-V method in the fingerprint identification field. Aceituno introduced as an

exhibit a 2009 report from the National Research Council, which was critical of

ACE-V. Despite its criticism, the report still referred to the method as “[t]he

technique used to examine prints made by friction ridge skin.” National Research

Council, supra, at 137; see also United States v. Baines,

(10th

Cir. 2009) (referring to ACE-V as the “process used for determining whether a

latent print matches a known print”). Moreover, courts have readily admitted

fingerprint identification using the ACE-V method.10 See, e.g., United States v.

Pena,

(1st Cir. 2009) (collecting cases); see also United States v.

Crisp,

(4th Cir. 2003) (noting that fingerprint identification

evidence has been admissible in criminal trials for more than a century). This court

is unaware of any case in which a court has sustained a Daubert challenge to a

10 Many of these cases predate the 2009 National Research Council report.

18 fingerprint identification made using the ACE-V method. Indeed, the Fourth Circuit

has noted the “strong expert and judicial consensus” regarding the reliability of

ACE-V fingerprint identifications. Crisp,

. Given this consensus, and

the widespread adoption of the ACE-V structure for fingerprint identifications, this

factor supports admitting Cornell’s expert testimony.11

F. Reproducibility

Finally, Aceituno asked the court to consider reproducibility. At the

evidentiary hearing, Cornell all but reproduced her process—taking the court

through the details of each step in her analysis. The documentation required as part

of the identification, though minimal, nonetheless allowed Cornell to repeat and

demonstrate to the court her detailed evaluation of the fingerprints. As part of the

verification stage of the ACE-V method, her results were also peer reviewed and,

essentially, reproduced.

Cornell’s report, by itself, did not adequately describe the methodology

employed in this case. By testifying to the operating procedures she used within

each step, however, Cornell supplemented her report with sufficient details and

explanations. The lack of a known error rate (that properly accounts for the

11 However, in light of ACE-V’s shortcomings—as identified by Triplett and the

National Research Council’s report—the court concludes that the proponent of a fingerprint expert must do more than simply describe the methodology as the “widely accepted ACE-V method.” See, e.g., Baines,

(“The ACE-V system is a procedural standard but not a substantive one.”). By itself, the ACE-V method describes neither a technique nor a specialized skill. To be admissible, the specific manner in which the expert employs the ACE-V method must satisfy the Daubert/Kumho principles. 19 simplicity or complexity of the latent print) raises concerns about the methodology.

But, in light of Cornell’s detailed testimony at the evidentiary hearing, the court

finds Cornell’s version of the ACE-V methodology sufficiently reliable.

II. The Government’s Expert Reliably Applied the ACE-V Method

Aceituno also argues that Cornell did not reliably apply the ACE-V method.

Specifically, Aceituno challenges Cornell’s documentation, the subjective judgments

made using the SOPs, and the errors in marking features.

A. Documentation

Aceituno first argues that the SOPs do not require enough documentation to

determine the reliability of the expert’s application of the ACE-V method and the

SOPs themselves. The SOPs require documentation in the form of notations and

markings—rather than narrative explanations—when analyzing a fingerprint.

Cornell testified to her adherence to the SOPs’ requirements for documentation.

Further, over several hours in the courtroom, Cornell explained her notations on a

demonstrative overlay of the fingerprint image to show her process. Any deficiencies

in her documentation were cured by her testimony.

B. Subjectivity of Standards

Aceituno next argues that the lack of specificity in the SOPs renders their

application highly subjective. Cornell testified that differences in the points of

identification on the latent and known prints were “within tolerance,” that is,

within a permissible margin of error. Triplett testified that the notion of “tolerance”

20 was too subjective, especially because the SOPs did not provide a numerical value

for tolerance. This debate is appropriate for the jury to hear in weighing Cornell’s

credibility. Aceituno does not argue that Cornell deviated from any particular

standards. Aceituno’s real challenge is to the lack of numeric standards for guiding

fingerprint analysis in general. The lack of numeric standards is a problem

seemingly endemic to fingerprint identification, but it does not render Cornell’s

application of ACE-V unreliable.

C. The Government Expert’s Errors

Finally, Aceituno argues that the errors made by Cornell and her peer

undermine the reliability of the entire identification. In her expert report, Triplett

identified two errors, prompting the government to ask Cornell to reexamine the

fingerprints. Cornell did so and she explained the errors in her live testimony. Any

errors in fingerprint identification go to the weight of her testimony and her

credibility as an expert. See Mooney,

. Aceituno will have the

opportunity to expose these errors to the jury on cross-examination or with his own

expert.

Having considered Cornell’s latent fingerprint identification through the lens

of Daubert and Kumho Tire, as well as the long line of cases admitting fingerprint

identifications using the ACE-V method, the court finds that Cornell’s use of the

ACE-V method is sufficiently reliable under Rule 702.

21 CONCLUSION

Aceituno’s motion in limine (doc. no. 94) is denied.

SO ORDERED.

__________________________ Landya McCafferty United States District Judge

October 25, 2023

cc: Counsel of Record

22