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.
General Laws c. 6, § 178H(s), as amended through St. 2006, c. 303, §§ 4 & 5, provides in pertinent part:
“(a) A sex offender required to register pursuant to this chapter who knowingly: (i) fails to register; (ii) fails to verify registration information; (iii) fails to provide notice of a change of address; or (iv) who knowingly provides false information shall be punished in accordance with this section.”
The indictment, tracking the pertinent language of G. L. c. 6, § 178H(a), reads as follows: “Tony Johnson, also known as James Coffman, also known as Anthony Johnson, also known as Anthony Ramon defendant herein, . . . on divers dates from on or about March 31, 2010 through and including on or about April 30, 2010, ... did knowingly: (i) fail to register; (ii) fail to verify registration information; (iii) fail to provide notice of a change of address; or (iv) provided false information, in violation of [G. L. c. 6, §] 178H(«)(1) & (2).”
The defendant had four previous convictions of failing to register as a sex offender.
The violation of probation was based on the commission of the instant offense as well as violations of “additional conditions.”
The Commonwealth also argued at trial that the defendant violated the *35statute by knowingly failing to provide an accurate secondary address, but does not press this point on appeal.
Specifically, the defendant claims that his prosecution “offends the fundamental principles of justice, fairness and due process guaranteed by the Fourteenth Amendment” because the authorities, namely the district attorney’s office, not only knew where he was, but were responsible for moving him out of State. Although the defendant frames his argument as a violation of due process, we construe it as a challenge to the sufficiency of the Commonwealth’s evidence.
The defendant signed the forms on March 24, 2006; June 27, 2006; and April 4, 2007.
Detective Duda is assigned to the sex offender registry unit.
The defendant cannot read and completed the form with Detective Duda’s assistance. The defendant testified that he was a special needs student while he attended school and that he left school altogether after repeating the seventh grade.
On April 26, 2010, Springfield police Detective John Aberdale conducted a routine audit of the information on the defendant’s sex offender registry form and went to 619 State Street to determine if the defendant was living at that address. Detective Aberdale discovered that the nonprofit organization, Springfield Community Partnerships, was located at 619 State Street and that the defendant was not living there. Detective Aberdale then changed the defendant’s status in the sex offender registry inquiry system (SORIS) by placing him “in violation,” which meant that he could be arrested from that point forward.
Although Boyd had known the defendant since childhood, she did not know his true name. At trial she referred to the defendant by his nickname “Black.”
The dissent has ignored this critical point and apparently accepts the defendant’s testimony as truthful.
Although neither the defendant nor the Commonwealth was required to produce evidence which would have resolved the issue whether the defendant had been placed in protective custody and, if so, on what dates, we are hard pressed to find a reason why something that could be so readily proved or disproved remained unanswered. In the end, however, the Commonwealth’s case was not undermined by the fact that it did not present evidence to rebut the defendant’s claim.
The dissent states that the defendant and his girlfriend were staying with Boyd on March 31, 2010. This assertion ignores our obligation to view the evidence in the light most favorable to the Commonwealth. Furthermore, even though Boyd’s testimony was “somewhat confusing and contradictory,” as the dissent posits, Boyd never testified that the defendant was living with her on March 31, 2010, while in response to the question, “He left in March?” she answered, “Yes.”
The subsequent offender trial took place four days after the trial on the failure to register charge.
This is especially true in light of the defendant’s “eleventh hour” request to continue the trial. See Commonwealth v. Johnson, 424 Mass. 338, 342 (1997); Commonwealth v. Lepper, 60 Mass. App. Ct. 36, 53 (2003).