In 1991, the defendant was convicted by a jury of aggravated rape and related offenses in Superior Court. Upon his release from prison he was classified as a level three sex offender and became subject to the registration requirements of G. L. c. 6, § 178FV2. On April 21, 2011, following a jury-waived trial, the defendant was found guilty of failing to register as required, in violation of G. L. c. 6, § 178H(a).2 In a separate proceeding before the same judge, the defendant was convicted of being a second offender, in violation of G. L. c. 6, § 178H(fl)(2).3 Thereafter, in a proceeding before the same judge the defendant admitted to a violation of probation in connection with another conviction, the hearing on which had been pending.4

The Commonwealth’s theory of guilt was that the defendant knowingly provided a false address when he registered at the Springfield police department on March 31, 2010, and that, even if the defendant had been residing at the address he provided on that date, he subsequently changed his address and knowingly failed to provide notice to the police of that change.5

*35At trial, the defendant admitted that he had notice of his status and his obligations under the statute, including the requirement of reporting a change in his address. He claimed, however, that he was in compliance with the statute because the Hampden County district attorney’s office had placed him in protective custody out of State during the time period specified in the indictment. The defendant filed motions for a required finding of not guilty at the close of the Commonwealth’s case and at the close of all the evidence, which were denied. In the motion filed at the close of all the evidence, the defendant argued, in essence, that because the Commonwealth did not rebut his testimony about being placed in protective custody, the evidence was insufficient to prove that he knowingly violated the statute.

On appeal, the defendant claims that his motions for a required finding of not guilty should have been allowed.6 He also contends that the judge erred by (1) admitting in evidence documents maintained by the Sex Offender Registration Board (SORB) and the Superior Court probation department, and (2) failing to inquire into the reasons why the defendant wished to be represented by different counsel at the second offender trial. For the reasons that follow, we affirm the conviction.

Background. The evidence permitted the judge to find the following facts. While the defendant was in prison he signed an acknowledgment of his duty to register on three separate occasions.7 Each time the defendant signed an acknowledgment form, Judit Morales, the SORB liaison at the Hampden County sheriff’s department, explained the statute’s requirements to him. Additionally, prior to March of 2010, during periods when the defendant was not incarcerated, he registered as a sex offender with the Holyoke and West Springfield police depart*36ments, and on one occasion he notified the SORB of his change of address.

By January 1, 2010, the defendant was living in Springfield. On February 12, 2010, he was placed on probation. He was supervised by probation officer Andrea Cadieux. At that time, the defendant reported that he was living at 700 State Street in apartment 315, in Springfield. The defendant later informed the probation department that he resided in apartment 215, and on a third occasion, in apartment 312. After the defendant missed a scheduled appointment with Cadieux on March 9, 2010, Cadieux attempted to contact the defendant using the addresses he had provided, but she was unsuccessful. Cadieux continued her efforts to contact the defendant during the month of April to no avail.

Meanwhile, on March 31, 2010, the defendant met with Detective Tracy Duda at the Springfield police department, where he completed a sex offender registration form.8 Detective Duda reviewed the statute’s requirements as they appear on the form and read them aloud to the defendant.9 The completed registration form stated that the defendant was living at 619 State Street in apartment 3L in Springfield, but, as the defendant conceded at trial, he never lived at 619 State Street.10 According to the defendant, the number “619” was written in error and he actually was living at “691” State Street in the home of Shatina Boyd. The discrepancy in the numbers is immaterial because the evidence showed that the defendant did not live at either address on March 31, 2010. Boyd testified that the defendant *37and his girlfriend, who was a close friend of Boyd’s, moved into her apartment at 691 State Street near Christmas in 2009, and stayed two or three months before leaving “around March.”11 Boyd further testified that near the end of the defendant’s stay, he was not living with her all the time. Rather, he was going “back and forth.” During the month of April, the defendant did not reside with Boyd, who was evicted on April 8. The defendant did not provide notice of a change of address.

The defendant testified in his own defense. He stated that he had been shot on New Year’s Day and again in early April, 2010, after which he became a material witness for the Hampden County district attorney’s office. That office, the defendant asserted, moved him to a motel in Connecticut at “the end of March” where he remained for “a month or a month and a half.” The defendant also stated that he testified before a Hampden County grand jury, but he did not specify when that occurred. According to the defendant, he was returned to Springfield at some point in April and remained homeless until he was arrested on April 30, 2010. The defendant identified his signature on the various registration and acknowledgment forms that had been introduced in evidence and admitted that he was aware of his obligations under the statute even though he could not read the forms himself.

1. Sufficiency of the evidence. As noted, the defendant claims there was insufficient evidence to support his conviction. Our review of the evidence, viewed in the light most favorable to the Commonwealth, see Commonwealth v. Latimore, 378 Mass. 671, 676-678 (1979), reveals a sufficient basis from which a rational finder of fact could have reasonably inferred that the defendant knowingly violated the statute.

At the outset, we observe that the judge was not required to believe the defendant’s claim that he was placed in protective custody.12 Determinations of witness credibility lie exclusively within the province of the trier of fact. Commonwealth v. Ianello, *38401 Mass. 197, 202 (1987). The judge, as trier of fact, was entitled to reject part or all of the defendant’s testimony. See Commonwealth v. Zanetti, 454 Mass. 449, 457 (2009). In this case, it is evident that the judge disbelieved the defendant. It is not surprising that he did so. The defendant’s testimony was inconsistent on a number of key points. For example, he claimed that he was living at 691 State Street on March 31, 2010, but also testified that the district attorney’s office had moved him to Connecticut at the end of March. At one point the defendant testified that he was in protective custody during the month of April, but he later stated that he was put in the motel in Connecticut right after he was placed on probation, which would have been in mid-February. The defendant further testified that he was arrested at the end of March, 2010, because he “needed to register” and was brought to the Springfield police department by State troopers, one of whom he identified by name. This assertion contradicts the defendant’s own chronology of events. Given the nature of the defendant’s testimony coupled with the absence of any corroborating evidence, it was not unreasonable for the judge to have rejected the defendant’s version of events.

We further observe that the Commonwealth was not required to present evidence to dispute the defendant’s claim.13 The state of the evidence at the close of all the evidence is reviewed only “to determine whether the Commonwealth’s position as to proof deteriorated after it closed its case.” Commonwealth v. Morgan, 449 Mass. 343, 349 (2007), quoting from Commonwealth v. Sheline, 391 Mass. 279, 283 (1984). See Commonwealth v. Dubois, 451 Mass. 20, 28 (2008), quoting from Commonwealth v. O’Laughlin, 446 Mass. 188, 203 (2006) (“Deterioration only occurs where the Commonwealth’s evidence of necessary elements ‘is later shown to be incredible or conclusively incorrect’ ”). “Where, as here, the evidence at trial *39‘turns solely on the credibility of [the defendant’s] witnesses,’ the Commonwealth’s case cannot deteriorate.” Commonwealth v. Gomez, 450 Mass. 704, 710-711 (2008), quoting from Commonwealth v. Platt, 440 Mass. 396, 404 (2003).

In any event, even if the defendant had been placed in protective custody at some point, there was ample evidence to support the conviction on the theory that the defendant was not living at 691 State Street on March 31, 2010. Indeed, Boyd’s testimony alone suffices to establish beyond a reasonable doubt that the defendant knowingly provided a false address to Detective Duda on March 31, 2010.14

There also was sufficient evidence to support the conviction on the ground that the defendant had changed his address without notifying the authorities. Even assuming that the defendant was returned to “the streets” of Springfield at the behest of the district attorney, this fact did not relieve him of his obligation to report that he was now homeless and was no longer living at 691 State Street. See Commonwealth v. Scipione, 69 Mass. App. Ct. 906, 907 (2007).

2. Admission of SORB and probation records. The defendant’s argument that the admission in evidence of records maintained by SORB and the probation department violated his right under the Sixth Amendment to the United States Constitution to confront witnesses is meritless. The SORB documents at issue consisted of verification forms and letters sent by SORB to the defendant at various addresses. The probation records consisted of an intake form and a letter sent to the defendant by Cadieux. In both instances, the person who created the documents at issue testified at trial and was subject to cross-examination. Thus, the defendant’s right of confrontation was not implicated. Moreover, as we recently held in Commonwealth v. Fox, 81 Mass. App. Ct. 244, 245 (2012), even in the absence of a witness who created the records, the admission in evidence *40of business records kept by SORB did not violate the defendant’s constitutional rights where the records were kept in the ordinary course of SORB’s affairs, were prepared and maintained by the public officials as required by the statute, and were not for the purpose of establishing an essential fact at trial. The records at issue undeniably satisfied these conditions.

We also reject the defendant’s contention that the SORB records were inadmissible because they included references or were addressed to aliases (“Tony Johnson” and “Anthony Ramon”) used by the defendant. The defendant did not object to the admission of the records on this basis, and even if he had objected, we discern no prejudice in view of the fact that the defendant acknowledged at trial that he had used those very same aliases.

3. Request for new counsel. On the morning of the day the subsequent offender trial commenced, defense counsel informed the judge that the defendant wanted to continue the case in order to hire his own attorney.15 Although the defendant was not given an opportunity to explain himself, the record does not disclose any valid reasons to discharge defense counsel. While the better course would have been to “permit [the] defendant to advance his reasons for wanting to discharge his attorney” so that the judge could exercise his discretion “on an informed basis,” Commonwealth v. Moran, 388 Mass. 655, 659 (1983), quoting from Lamoureux v. Commonwealth, 353 Mass. 556, 560 (1968), in order to demonstrate prejudice the defendant must present “a valid reason to discharge his attorney.” Commonwealth v. Moran, supra at 660. In the absence of any such reason, we have no basis for concluding that the judge abused his considerable discretion by not initiating further inquiry into the defendant’s request.16 See Commonwealth v. Clemens, 77 Mass. App. Ct. 232, 237-238 (2010) (although judge failed to provide defendant adequate opportunity to explain his reason*41ing, no abuse of discretion where there was lack of sufficient facts warranting new counsel).

Judgment affirmed.

(dissenting). I conclude that the evidence was insufficient to support the defendant’s conviction; therefore, I dissent.1

The Commonwealth alleged two things: that (a) on March 31, 2010, the defendant was not living at the address that he had provided to the Springfield police department, and (b) between March 31, 2010, and April 30, 2010, the defendant changed his address without notifying the authorities of the change.

The testimony at trial was that on March 31, 2010, the defendant met with Detective Tracy Duda of the Springfield police department’s sex offender registry unit for the purpose of fulfilling his obligation to register as a sex offender. At that time, the defendant and his girlfriend were staying with the girlfriend’s friend, Shatina Boyd, a tenant at 691 State Street, apartment 3L, in Springfield.2 Duda helped the defendant fill out the sex offender registration form, reviewed the requirements with him, and read the requirements aloud to him. The defendant, a special education student who dropped out of school after repeating the seventh grade, was unable to read.

*42The completed registration form contained several errors. The form listed the date of registration as the “third day of the 31st month” of 2010, and listed the defendant as Tony Johnson, a name that had been associated with the defendant in the past. Most importantly, the defendant’s address was listed, improperly, as 619 State Street, apartment 3L, instead of 691 State Street, apartment 3L.

Shortly after the defendant completed the registration form, he and his girlfriend were forced to leave 691 State Street because Boyd was evicted for having too many people and too much traffic in the apartment.3 Boyd’s testimony regarding the date when the defendant left her apartment, though somewhat confusing and contradictory, is consistent with the defendant’s testimony that he was living at the apartment on March 31, 2010.4

While the Commonwealth’s evidence showed that the defendant did not live at 619 State Street, the address on the form, the Commonwealth’s own witness, Boyd, substantiated that the numbers on the form were mistakenly reversed, by her testimony *43that the defendant and his girlfriend had been staying at her apartment at 691 State Street. Thus, the evidence did not establish beyond a reasonable doubt that the defendant provided a false address. As to the question whether the defendant was living at Boyd’s apartment on March 31, 2010, the date the form was filled in, while the Commonwealth’s evidence established that the defendant was not living at Boyd’s apartment on April 8 and thereafter, it did not establish beyond a reasonable doubt that the defendant was not living at that address on March 31. See note 4, supra. When asked, “When is the last time he lived your residence?” Boyd responded, “I’ll say the end of March . . . .” Moreover, other than April 8, Boyd’s testimony in general as to time periods was based on estimates and attempted reconstructions, none of which is sufficient to establish beyond a reasonable doubt that the defendant was not living at that address on the date he signed the form.5 The Commonwealth’s evidence thus was not sufficient to prove the charge of giving a false address beyond a reasonable doubt.

In his defense at trial the defendant testified that during the first part of April, he suffered a gunshot wound and, thereafter, became a material witness for the Hampden County district attorney’s office. He later testified as a Commonwealth witness before a Hampden County grand jury. During the time he was a material witness, for most of April, 2010, the defendant was in protective custody, living in a motel in Connecticut at the direction of a Hampden County assistant district attorney referred to by the defendant by name.

Finally, the defendant testified that, after he appeared before the grand jury as a Commonwealth witness, the district attorney’s office returned him to Springfield. After his return to Springfield, he was homeless and living on the street prior to his arrest on April 30, 2010, on the current charges. The defendant’s testimony on these key matters was essentially unchallenged.

Even if the Commonwealth’s evidence established that the *44defendant failed to comply with the registration requirements, the Commonwealth has failed to make the necessary showing of criminal intent.6,7 “Concerning whether the defendant ‘knowingly’ provided false information, G. L. c. 6, § 178H (a), does not require the Commonwealth to prove that a defendant intended to deceive the board, but the Commonwealth must prove that he knew the information was false.” Commonwealth v. Rosado, 450 Mass. 657, 662 (2008), citing Commonwealth v. Fondakowski, 62 Mass. App. Ct. 939, 940 (2005) (sufficient evidence that defendant knowingly provided false information to board where he had home in Northampton but placed “HOME-LESS” as his address and “Any-where I can live” as his city). On this record, the evidence was insufficient to prove beyond a reasonable doubt that the defendant knowingly provided false information about his residence or knowingly failed to provide notice of his intent to change his address.

Accordingly, I would reverse the conviction of failure to register as a sex offender and direct the entry of a judgment of not guilty on that charge. While the order finding a violation of probation and imposing sentence on the offense on which the violation of probation was found is not part of this appeal, in my view, because the conviction of failing to register in the present case, which I believe should be reversed, was one of the main bases for finding a violation of probation, the sentence imposed upon the revocation of probation should also be reconsidered.