A jury in the Superior Court convicted the defendant on an indictment charging him with armed assault with intent to rob. He was acquitted on an indictment charging him with armed assault with intent to murder. The defendant appealed. We granted his application for direct appellate review. He argues three claims of error. First, the defendant contends that his pretrial motion to suppress out-of-court identifications made by two eyewitnesses was improperly denied. Second, he argues that the trial judge erred in admitting in evidence a surveillance videotape of another robbery, allegedly committed by the defendant. Third, the defendant argues that the judge erred in permitting a Commonwealth witness, Hubert Paquette, a police officer in Rhode Island, to testify that he knew the defendant, and that he recognized the individual on the surveillance videotape as the defendant. We conclude that the out-of-court identifications were admitted properly, and that the surveillance videotape was admissible for the purpose of assisting the jury in evaluating the reliability of the challenged identifications. We further conclude that the testimony of Hubert Paquette should not have been admitted, but that its admission was not prejudicial. Accordingly, we affirm the defendant’s conviction.
1. Identification evidence. We recite the relevant facts found by the judge on the defendant’s motion to suppress, with minor additions from the transcript. On February 20, 1990, an armed man entered the First Federal Savings Bank in Somerset and attempted to rob it. Laurie Gervasio1 and Jeanie Mizher, employees of the bank, witnessed the attempted robbery. They described the gunman as approxi*359mately six feet tall, slender, fair skinned, wearing a knit cap and a tan or gold overcoat. They described his face as long and thin and stated that he had an extremely large nose and very distinctive nervous mannerisms. The man fled the bank after seeing a police officer through the bank window. The officer pursued the robber, who fired shots at his pursuer at least twice. Several minutes later, while making his escape in a waiting vehicle, the robber also fired his gun at some bystanders.
Gervasio testified that the robber walked within three feet of her desk as he approached the teller. She had a clear view of him and observed him throughout the robbery. Mizher also had an unobstructed view of the robber. Her attention was drawn to him when he yelled instructions to the teller. Mizher watched him until he left the bank, approximately three minutes later.
After the robbery, Gervasio went to the East Providence police station to view two lineups of eight men each. She did not see the robber among these individuals. She then went to the Somerset police station and assisted an officer in making a composite drawing of the robber. The day following the attempted robbery, Mizher and Gervasio separately viewed about 200 color photographs. Neither witness selected a photograph from this array. Both women stated that they were positive they could identify the robber if they saw him again.
Two days later, on February 23, the two women were shown another photographic array consisting of eight photographs. Neither identified the robber from this array. However, Mizher selected a photograph from this array as a picture which might give the police some idea of the robber’s appearance. She was sure the person depicted in this photograph was not the robber.2
On February 23, there was an armed bank robbery in Rhode Island. The robber was not apprehended, but the robbery was recorded by the bank’s surveillance camera. The *360police watched the videotape of the robbery and noticed that the individual on the videotape (Rhode Island robber) resembled Gervasio’s composite drawing of the Somerset robber. The mannerisms displayed by the Rhode Island robber, and the similar modus operand!, led the police to believe that the two banks had been robbed by the same individual. Also on February 23, a Somerset detective learned from a colleague of a recent armed bank robbery in Salem, New Hampshire, having characteristics similar to the Somerset and Rhode Island robberies.
On February 24, the police showed the videotape to Gervasio. She was warned to remain unbiased as she watched it. Within seconds of observing the man on the videotape, Gervasio stated that he was the man who robbed the Somerset bank. The police later showed the videotape to Mizher who also identified the man, without hesitation, as the Somerset bank robber.
On February 26, the East Providence police department began showing the surveillance videotape to its officers as they came on duty. Two police officers who were former correction officers recognized the man in the videotape as Thomas Austin, who had previously been incarcerated. The police obtained two photographs of the defendant and placed one of them in a photographic array consisting of twelve photographs. This array was shown to both witnesses. Mizher chose the defendant’s photograph immediately. Gervasio stated that the defendant’s photograph resembled the robber but that the man in the photograph had skin that was darker than the robber’s skin. An officer then showed the second photograph of the defendant to Gervasio. This photograph was of a better quality and depicted the defendant with a lighter complexion. Gervasio identified him as the Somerset robber.
The defendant was arrested, pursuant to a warrant, and placed in a lineup with four other men. Gervasio and Mizher *361viewed the lineup separately and both immediately identified the defendant as the man who robbed the Somerset bank.3
2. The defendant argues that the judge erred in denying his motion to suppress the identifications made by Gervasio and Mizher when they viewed the videotape. He claims the identification procedure was unnecessarily suggestive in violation of his due process rights under art. 12 of the Declaration of Rights of the Massachusetts Constitution. See Commonwealth v. Johnson, 420 Mass. 458 (1995) (if defendant satisfies burden of demonstrating that witness was subjected to unnecessarily suggestive identification procedure, prosecution is barred from introducing that confrontation in evidence at trial). After a hearing, and based on the facts set forth above, the judge concluded that the out-of-court identifications were admissible because the witnesses were “reliable” and thus there was no “substantial likelihood of irreparable misidentification.” The identification procedure using the surveillance videotape was similar to a one-on-one confrontation between the suspect and witnesses Gervasio and Mizher. Such showup identifications are disfavored because they are viewed as inherently suggestive. See Commonwealth v. Johnson, supra at 461; Commonwealth v. Santos, 402 Mass. 775, 781 (1988). See also Stovall v. Denno, 388 U.S. 293, 301-302 (1967). Nonetheless, a one-on-one pretrial identification raises no due process concerns unless it is determined to be unnecessarily suggestive. Whether an identification procedure is “unnecessarily” or “impermissibly” suggestive, see Commonwealth v. Thornley, 406 Mass. 96, 98-99 (1989), involves inquiry whether good reason exists for the police to use a one-on-one identification procedure, see 1 W.R. LaFave & J.H. Israel, Criminal Procedure § 7.4 (b), at 581 (1984), bearing in mind that this court has said that “[ejxigent or special circumstances are not a prerequisite to such confrontations.” Commonwealth v. Harris, 395 Mass. 296, 299 (1985). See Commonwealth v. Barnett, 371 Mass. *36287, 92 (1976), cert, denied, 429 U.S. 1049 (1977); Commonwealth v. Coy, 10 Mass. App. Ct. 367, 371 (1980).
Relevant to the good reason examination are the nature of the crime involved and corresponding concerns for public safety; the need for efficient police investigation in the immediate aftermath of a crime; and the usefulness of prompt confirmation of the accuracy of investigatory information, which, if in error, will release the police quickly to follow another track. Commonwealth v. Barnett, supra. The analysis cannot be generalized. Each case must be resolved on its own peculiar facts, considering as well that the existence of “good reason” presents a question of law for the appellate court to resolve on the facts found by the motion judge. See Commonwealth v. Colon-Cruz, 408 Mass. 533, 538-539 (1990); Commonwealth v. Barnett, supra at 91.
The police had extremely good justification in this case for not resorting to a different identification procedure. Three armed bank robberies (in New Hampshire, Massachusetts, and Rhode Island) had occurred within a few days of each other. Two percipient bank managers had confronted the Somerset robber, and these witnesses had examined over 200 photographs and failed to make an identification. The witnesses were certain, however, that they could identify the Somerset robber if they saw him again, and one of them had assisted in the preparation of a composite drawing of the criminal. The police could take into consideration that the percipient witnesses appeared unusually reliable and nonsuggestible.
The Rhode Island and New Hampshire robberies bore a high degree of similarity to the modus operandi of the Somerset robbery, and the man who appeared in the videotape of the Rhode Island robbery resembled the man depicted in the composite drawing. The police were keenly aware that at least one dangerous bank robber was at large, and that whoever was involved could either escape altogether or strike *363again with possible injury to, or loss of, human life.4 The police acted responsibly in concluding that a prompt viewing by the witnesses of the surveillance tape from the Rhode Island robbery was needed. Specifically, the police needed to determine, as quickly as possible, whether the robberies were committed by a single individual. Based on the identification by the witnesses (or the lack thereof), the police in these communities would know whether they were dealing with one bank robber or more, and could focus their investigation accordingly. If the witnesses identified the man in the videotape as the Somerset robber, the Somerset police would have access to a photographic representation of the man, in addition to the composite drawing on which they were relying.
The defendant does not suggest that an alternate identification procedure was available and should have been employed. He argues instead that the police should have forgone attempting to establish a connection between these three crimes until such time as the perpetrator of the Rhode Island robbery had been identified or apprehended, opening the possibility of identification by lineup or traditional photographic array. This suggestion appears feasible only in hindsight. At the time the videotape was shown to Gervasio and Mizher, the police could not have known that the man in the videotape would be recognized promptly by members of the East Providence police department. Facing robberies in three States, the police departments involved could not make effective determinations on how to proceed in attempting to locate what might have been several perpetrators.
The identification made from the surveillance videotape confirmed that one man had robbed the Somerset and Rhode Island banks, and strengthened the inference that he had also *364been responsible for the New Hampshire robbery. That valuable information in turn led to the identity of a suspect in the Somerset robbery and caused the police promptly to arrange further pretrial identifications by the witnesses of the defendant through a photographic array and a lineup which are not challenged as improper in any respect. We conclude that, in the circumstances, which included a serious risk to public safety posed by a series of crimes having a similar modus operand! and eyewitnesses who appeared exceptionally non-suggestible, the police had good reason for what they did, and the surveillance videotape identification was not, as a result, unnecessarily suggestive.
3. The defendant also argues that the judge erred in admitting the videotape of the Rhode Island robbery because it constituted prejudicial evidence of other bad acts. While the point is close, we think the admission of the videotape was within the scope of the judge’s discretion. See Commonwealth v. Jackson, 384 Mass. 572, 578-579 (1981). The videotape was admitted for the limited purpose of assisting the jury in assessing the reliability of the witnesses’ identification of the defendant as the person depicted in the videotape. Thus, it was admitted on the same basis and for precisely the same purpose as were the photograph of the defendant in the lineup and the photographic arrays shown to the witnesses at the various stages of the police investigation. Testimony connected with the admission of the videotape focused exclusively on the degree of certainty exhibited by the witnesses in their identification of the man depicted in the videotape as the Somerset robber. Admission at trial of the photographs which formed the basis of a witness’s out-of-court identification of the defendant is relatively routine. See K.B. Smith, Criminal Practice and Procedure §§ 466-468 (1983 & Supp. 1995). As the Appeals Court observed in a similar case, “the [identification procedures] were the major investigatory tool which fixed suspicion on the defendant, and both prosecution and defense had an interest in arguing whether a positive identification of the defendant on the basis *365of the [photographic representations] was plausible.” Commonwealth v. Smith, 29 Mass. App. Ct. 449, 452 (1990).
The videotape, however, was not amenable to the sanitization procedures on which this court has insisted when a photographic array shown to a jury consists of police “mug shots.” See, e.g., Commonwealth v. Blaney, 387 Mass. 628, 637-640 (1982); Commonwealth v. Smith, supra at 452-453. We would be reluctant to conclude that it was, for that reason, categorically inadmissible. It is, in our opinion, analogous to the newspaper articles admitted for explanatory or foundation purposes in the case of Commonwealth v. Jackson, 384 Mass. 572, 578-579 & n.2 (1981), even though those articles strongly suggested that the defendant had committed murders other than the one for which he was being tried. As was done in the Jackson case, the judge here gave strong curative instructions to the jury at several points in the trial regarding the nature of the videotape and its limited use. We assume that the jury listened to and followed these instructions. See Commonwealth v. Gallagher, 408 Mass. 510, 518 (1990). There was no error.5
4. We agree with the defendant that the nonexpert opinion testimony of Hubert Paquette should not have been admitted. Paquette, whose testimony was of brief duration, stated that he had been acquainted with the defendant since 1977, saw him on a daily basis between 1978 and 1980, and periodically between 1980 and 1983.6 He then testified that he had *366viewed the surveillance videotape, and that he determined the man in the videotape to be the defendant.
“The competency of . . . [the opinion evidence of a nonexpert] rests upon two necessary conditions: first, that the subject matter to which the testimony relates cannot be reproduced or described to the jury precisely as it appeared to the witness at the time; and second, that the facts upon which the witness is called to express his opinion, are such as men in general are capable of comprehending and understanding.” Commonwealth v. Nassar, 351 Mass. 37, 41-42 (1966), quoting Commonwealth v. Sturtivant, 117 Mass. 122, 137 (1875). For the purpose for which the videotape was admitted in evidence, the opinion of Paquette that the defendant was the man in the videotape was inadmissible. The jury were capable of viewing the videotape and drawing their own conclusions regarding whether the man in the videotape was the defendant without the assistance of Officer Paquette’s testimony. Cf. Commonwealth v. Vitello, 376 Mass. 426, 459-460 & n.29 (1978) (following Nassar but holding that officer could properly testify that photograph chosen by witness depicted defendant because defendant’s appearance had changed since time of robbery). See also United States v. Jackman, 48 F.3d 1, 4-5 (1st Cir. 1995) (holding admissible nonexpert opinion testimony identifying a defendant from a surveillance photograph “when the witness possesses sufficiently relevant familiarity with the defendant that the jury cannot also possess, and when the photographs are not either so unmistakably clear or so hopelessly obscure that the witness is no better-suited than the jury to make the identification”).
Admission of this testimony did not constitute reversible error. The evidence pointing to the defendant was overwhelming and the officer’s testimony was merely cumulative of other identification evidence properly admitted against the defendant. See Commonwealth v. Nassar, supra at 42; Commonwealth v. Anderson, 19 Mass. App. Ct. 968, 969 (1985).
Judgment affirmed.
At the time of the attempted robbery, Laurie Gervasio was known as Laurie Houde. There is some discrepancy in the record as to the spelling of her first name. We shall refer to her simply as Gervasio.
The defendant’s photograph was not included in either of these arrays, nor was he present in the lineups.
The defendant does not argue that either the photographic array or the lineup from which he was identified was suggestive.
At the hearing on the defendant’s motion to suppress, a Somerset police officer testified to the urgency and concern felt by the police department:
“I was concerned there was a guy that fired shots at police and at citizens that was holding up banks. The [modus operand!] fit the description of bank robberies throughout the area, as far away as Salem, New Hampshire; and we believed we had a guy out there that was going to rob a bank a day until somebody was killed.”
The defendant argues that the videotape did not meet the standard for admissibility of “other bad acts” evidence set out in Commonwealth v. Jackson, 417 Mass. 830, 836 (1994). That case was concerned with the admission of evidence of a bad act other than the one for which the defendant was on trial used as proof of the identity of the perpetrator of both acts because of the unusual and highly distinctive way in which the acts were committed. Here, the videotape was admitted for a different (and a more limited) purpose. The decision in the Jackson case relied on by the defendant is not on point.
Paquette was a police officer in Rhode Island and had previously been a guard at the prison where the defendant had been incarcerated. His testimony brought neither of these facts to the attention of the jury.