The defendant, Richard Felt, is the subject of a petition for commitment under G. L. c. 123A, § 12. A judge in the Superior Court allowed a motion for the defendant’s counsel to be present during interviews conducted by qualified examin*317ers pursuant to G. L. c. 123A, § 13 (a) (§ 13 [a]).1 One of the two qualified examiners refused to conduct the interview with counsel in the room and submitted to the court her qualified examiner report based on her review of the defendant’s records only. The questions we consider in this case are whether the “examination” that a qualified examiner must undertake under § 13 (a) as the first step of a sexually dangerous person commitment process must include a personal interview of the defendant in accordance with the terms of a court order permitting his counsel to be present; and, if so, what consequences flow from the failure of the qualified examiner to conduct such an interview. We conclude that a personal interview is generally a required component of a § 13 (a) examination, regardless of whether counsel is present. Nevertheless, in the circumstances of this case, dismissal of the Commonwealth’s petition was not warranted as a remedy for the refusal of one of the qualified examiners to conduct the interview with counsel in attendance, where the other qualified examiner personally interviewed the defendant as part of his § 13 (a) examination and filed with the court a report expressing the opinion that the defendant is a sexually dangerous person. On remand, however, the Commonwealth may not use at trial the report or testimony of the qualified examiner who refused to interview the defendant.

1. Background. In 1988, a jury found the defendant guilty of indecent assault and battery of a victim under the age of fourteen in violation of G. L. c. 265, § 13B, after a six year old boy reported that the defendant had assaulted him in a locker room in Melrose. The Appeals Court affirmed the defendant’s conviction in an unpublished memorandum and order issued pursuant to its rule 1:28. While serving a sentence on the 1988 conviction, the defendant escaped from prison and fled to Maine, where he subsequently was convicted of several sexual offenses. In 2005, *318after serving his Maine sentences, the defendant was transferred back to Massachusetts to complete his sentence on the 1988 conviction and to serve a sentence for escape, G. L. c. 268, § 16.

In July, 2011, before the defendant completed his sentences in Massachusetts, the Commonwealth filed a petition to commit him as a sexually dangerous person under G. L. c. 123A, § 12 (b). On October 6, 2011, a judge of the Superior Court found probable cause to believe the defendant was a sexually dangerous person, and the defendant was committed to the Massachusetts Treatment Center (treatment center) for sixty days for examination and diagnosis under the supervision of two qualified examiners pursuant to § 13 (a). Before any personal interviews with the qualified examiners occurred, the defendant filed a motion for an order authorizing the defendant’s counsel to be present for the interviews, as well as for audio and audio-visual recording of them. The judge allowed the order by agreement “as to the presence of counsel at the evaluation,” and the defendant withdrew the request for audio or audio-visual recording.

Thereafter, one of the qualified examiners interviewed the defendant with counsel present for the entire interview. However, when the second qualified examiner met with the defendant to conduct a personal interview, she refused to proceed with the interview while counsel was in the room, and the interview did not take place. On November 14, 2011, both qualified examiners filed with the court their reports opining that the defendant was a sexually dangerous person. The report of the second qualified examiner stated that it was based solely on information from records that were made available to her at the treatment center, as well as a record package prepared by the Commonwealth.2 On November 18, the Commonwealth petitioned for trial pursuant to G. L. c. 123A, § 14 (a), a date within sixty days of the defendant’s commitment to the treatment center.

On December 14,2011, the defendant filed a motion to dismiss the Commonwealth’s petition on the ground that because one of the qualified examiners did not interview the defendant, the Commonwealth did not meet its burden of filing within forty-five days of the judge’s probable cause finding two qualified *319examiner reports meeting the requirement of § 13 (a) that they be based on an “examination.” A different Superior Court judge (motion judge) allowed the defendant’s motion to dismiss, concluding that § 13 (a) requires a personal interview where the person named in the petition does not refuse to be interviewed and, because the Commonwealth had not filed two qualified examiner reports that were compliant with § 13 (a) within the strict deadlines set forth in that section, dismissal was required. The Commonwealth appealed, and we transferred the case to this court on our own motion. The defendant’s release was stayed pending appeal.

2. Discussion. In reviewing a motion to dismiss a G. L. c. 123A petition, we examine whether the motion judge abused his discretion or committed other legal error. See Commonwealth v. Gagnon, 439 Mass. 826, 830 (2003).

The commitment and release of sexually dangerous persons is governed by G. L. c. 123A.3 This court has recognized that a personal interview need not occur under § 13 (a) where a defendant refuses to speak to a qualified examiner in connection with the commitment proceeding. See Commonwealth v. Connors, 447 Mass. 313, 315, 319-320 & n.10 (2006) (defendant has right not to speak with qualified examiners in connection with § 13 [a] examination based on patient-psychotherapist privilege, G. L. c. 233, § 20B, and constitutional privilege against self-incrimination). This case, however, presents a different issue, because here the defendant appeared at the interview prepared to speak to the qualified examiner with his attorney in attendance, in accordance with the court order authorizing counsel’s presence.4 It was the qualified examiner who refused to conduct the interview, because she objected to the presence of the defendant’s attorney. Therefore, the question before us is whether an *320interview is required when the interviewer, and not the defendant, refuses to conduct an interview.* ***5

We begin with the language of the statute, as “the principal source of insight into legislative purpose.” Commonwealth v. Poissant, 443 Mass. 558, 562 (2005) (quotation and citation omitted). Section 13 (a) provides:

“If the court is satisfied that probable cause exists to believe that the person named in the petition is a sexually dangerous person, the prisoner or youth shall be committed to the treatment center for a period not exceeding [sixty] days for the purpose of examination and diagnosis under the supervision of two qualified examiners who shall, no later than [fifteen] days prior to the expiration of said period, file with the court a written report of the examination and diagnosis and their recommendation of the disposition of the person named in the petition.”

The word “examination” is not defined, although in prior cases we have suggested that the terms “examination” and “interview” in the context of § 13 (a) are essentially interchangeable. See Commonwealth v. Connors, 447 Mass. at 317 n.7, quoting Commonwealth v. Poissant, supra at 559 n.1 (“there is, in fact, ‘no meaningful distinction between the terms’ ”). Moreover, and more significantly, § 13 (a) specifically requires a sixty-day commitment of the person claimed to be a sexually dangerous person “for the purpose of examination and diagnosis” by the qualified medical examiners. We understand this choice of language — the mandatory, time-limited period of commitment and the specific statement of the commitment’s purpose — to mean that the Legislature intended the § 13 (a) examination to include personal interviews. We do so because there would be no other reason to commit a defendant at this point in the process,6 given that the qualified examiners could examine the defendant’s *321records on their own, regardless of whether he were present. See Commonwealth v. Bradway, 62 Mass. App. Ct. 280, 288 (2004) (reading § 13 [a] to require “a clinical component to the qualified examiners’ review” because of statute’s provision that person must be committed for “the purpose of examination and diagnosis under the supervision of two qualified examiners”).* *****7

Moreover, the requirement that qualified examiners conduct personal interviews advances the compelling purpose of commitment proceedings to investigate “a person’s current mental condition,” Commonwealth v. Bruno, 432 Mass. 489, 503 (2000), in order to decide “[wjhether [the] person suffers from a mental abnormality or personality defect, as well as the predictive behavioral question of the likelihood that a person suffering from such a condition will commit a sexual offense,” Johnstone, petitioner, 453 Mass. 544, 549 (2009), quoting Commonwealth v. Dube, 59 Mass. App. Ct. 476, 483 n.12 (2003).8 A review of existing criminal and patient records, without an in-person assess*322ment of the defendant, is likely to present an incomplete and perhaps incorrect picture of the defendant’s current state of mind. See, e.g., Commonwealth v. Boyer, 61 Mass. App. Ct. 582, 584, 586 (2004) (Commonwealth’s expert witness, who had conducted review of defendant’s record for purposes of probable cause determination under G. L. c. 123A, § 12 [c], and had concluded defendant was sexually dangerous person, recanted opinion at time of trial based principally on personal interviews with defendant and his wife). We therefore conclude that § 13 (a) requires qualified examiners to conduct personal interviews in accordance with the terms mandated by the court where a defendant does not refuse to be interviewed.* **9

In advancing a contrary reading of § 13 (a), the Commonwealth points to the statutory provision governing petitions for examination and discharge by those committed as sexually dangerous persons, G. L. c. 123A, § 9 (§ 9). Section 9 both contains an express directive that the examinations of a petitioning sexually dangerous person by two qualified examiners “include[] personal interviews” and penalizes a petitioner’s refusal to be interviewed by directing that his petition for discharge be dismissed.10 The Commonwealth argues that the presence of these explicit provisions in § 9 forecloses the possibility that the word “examination” by itself as used in § 13 (a) requires a personal interview. We disagree.

The Legislature amended § 9 in 1987 to add the clause “including personal interviews” as well as the penalty for a petitioner’s refusal to be interviewed — twelve years before the Legislature *323added § 13 (a) to G. L. c. 123A as part of a comprehensive statutory overhaul designed to improve the sex offender registration system and to reestablish civil commitment and community parole supervision for life for certain sex offenders. See, respectively, St. 1987, c. 116, and St. 1999, c. 74, § 58. Given the temporal gap between these enactments, we do not place much weight on the differences in language between §§ 9 and 13 (a).11 Rather, we understand these differences simply to reflect what appears to be imprecise use of language in separate statutory amendments.12 Cf. Santos, petitioner, 461 Mass. 565, 571 (2012) (interpreting language in §§ 9 and 14 [c], listing slightly different *324types of records deemed admissible at trial of petitions for discharge and for commitment, respectively, to permit admission of same types of records in both because “[w]e construe the two related statutes in a manner that makes them consistent with one another”).

Finally, contrary to the Commonwealth’s contention, it was not the obligation of the defendant to bring to the attention of the judge the qualified examiner’s refusal to conduct the interview in accordance with conditions set by the court order before expiration of the sixty-day period. “Although qualified examiners are independent experts appointed by the court, . . . [i]t is the Commonwealth’s responsibility to ensure that the treatment center performs the examinations in a timely manner.” Gangi v. Commonwealth, 462 Mass. 158, 162 (2012) (quotations and citations omitted).

The question then becomes what happens where, as here, one qualified examiner has violated § 13 (a) by declining to interview the defendant. The defendant argues, and the motion judge agreed, that the proper remedy is dismissal of the Commonwealth’s petition. We decide otherwise.

Dismissal is warranted when a misstep in the commitment process under G. L. c. 123A results in the defendant’s commitment to the treatment center for more than the sixty-day period specified in § 13 (a). See, e.g., Gangi v. Commonwealth, 462 Mass. at 159, 160-161 (dismissal required where Commonwealth filed petition for trial sixteen days beyond sixty-day statutory deadline); Commonwealth v. Kennedy, 435 Mass. 527, 530 (2001) (dismissal required where defendant was committed for more than forty-five days on three separate occasions with no qualified examiner reports on file, resulting in detention for period “vastly in excess of the maximum [period of detention] allowed by the statute”). Dismissal is proper in such cases, we have explained, because “the liberty interests at stake compel strict adherence to the time frames set forth in the statute.” Id. at 531.

By contrast, the error in this case did not infringe on the defendant’s liberty interest. Both qualified examiners timely filed their reports under § 13 (a), and the Commonwealth timely filed a petition for trial pursuant to § 14 (a). Cf. Commonwealth v. Gagnon, 439 Mass. 826, 827, 830-831 (2003) (dismissal not required where qualified examiners’ reports were filed after *325forty-five day statutory deadline because qualified examiners submitted reports and Commonwealth filed petition for trial all within sixty-day period of commitment in § 13 [a]). Contrary to the conclusion of the motion judge, a report that is based solely on a record review still qualifies as a “report of examination and diagnosis” under § 13 (a). See Commonwealth v. Connors, 447 Mass. 313, 318-320 (2006) (qualified examiner reports still admissible where defendant refuses to be interviewed personally). Additionally, this court has made clear that the Commonwealth may properly proceed to trial in a commitment proceeding where “at least one of the two qualified examiners . . . opine[s] that the [defendant] [is] sexually dangerous.”13 Johnstone, petitioner, 453 Mass. at 553. Because the two qualified examiner reports and the Commonwealth’s petition for trial were timely filed within the sixty-day period specified in § 13 (a), and at least one of those reports was based on a personal interview with the defendant and concluded that the defendant is a sexually dangerous person,14 dismissal of the petition is not appropriate.15

However, a qualified examiner’s refusal to interview the defendant under the terms of a court order, where the defendant agrees to be interviewed under those terms, cannot simply be ignored. Permitting the Commonwealth to introduce the testimony or report of a qualified examiner who refused to conduct an interview would present an incomplete picture of the defendant’s current sexual dangerousness and raises questions about the fairness of the commitment proceeding. As discussed in Commonwealth v. Connors, 447 Mass. at 317-319 & nn.8-9, we are wary of conduct in c. 123A proceedings that “would have allowed ‘a distorting effect on the fact finder’s role.’ ” See id. at 318-319, quoting Commonwealth v. Wayne W., 414 Mass. 218, 231 (1993). Accordingly, where a qualified *326examiner declines to conduct a personal interview as part of a § 13 (a) examination, the qualified examiner’s report and testimony shall be inadmissible at any subsequent trial conducted under G. L. c. 123A, § 14.

3. Conclusion. The judgment allowing the defendant’s motion to dismiss is vacated, and the case is remanded to the Superior Court for further proceedings consistent with this opinion.

So ordered.