The defendant was convicted of two counts of armed robbery while masked, G. L. c. 265, § 17, arising out *31of a holdup of a bank in Beverly. On appeal, he contends that his motion to suppress three statements used against him at trial should have been allowed. We discuss separately the circumstances in which each of the statements was made and the propriety of its admission. We conclude that admission of one of the statements was error but that it was harmless beyond a reasonable doubt. We therefore affirm the convictions.
1. The first statement. The defendant had provided confidential information to Salem police Sergeant Richard Urbanowicz which had helped solve earlier bank robberies. In the weeks following the Beverly bank robbery, the defendant, without indicating his own involvement, provided confidential information to Sergeant Urbanowicz concerning that robbery. Urbanowicz passed the information along to Beverly Detective John Bianchi. Because the Beverly police had information of their own linking the defendant’s car to the robbery, he became a suspect. At Detective Bianchi’s request, Sergeant Urbanowicz revealed the defendant’s identity to the Beverly officers and agreed to try to set up a meeting with the defendant. Although the defendant later said he had become aware that he was a suspect, he agreed to the meeting.
Detective Bianchi and Captain John Cassola, also of the Beverly police, arranged to meet the defendant in his home on a Friday morning about a month after the robbery for the express purpose of questioning him about the robbery. When the police arrived, the defendant was home with his children. The atmosphere was relaxed and the defendant spoke freely. Although he did not reveal that he was a participant, he described how the robbery was carried out, and he named several individuals who had been involved in it. The defendant agreed to allow the officers to take his photograph to include in an array to be shown to bank employees. At no point during the interview did the officers give the defendant the Miranda warnings. When told that the photographs would also be shown to two witnesses who were present when the getaway car was stolen, the defendant made the first statement *32in issue: “I never said I wasn’t there when the car was stolen.”
The defendant moved to have the statement suppressed on the ground that, before making it, he had not been given the Miranda warnings. The judge ruled that the warnings were not required because the defendant was not in custody. See Commonwealth v. Bryant, 390 Mass. 729, 736 (1984). There is ample evidence to support the conclusion that the defendant was not in custody before making the statement, and on appeal there is no contention that the environment in which it was made was coercive. Instead, the defendant focuses on his previous relationship with Sergeant Urbanowicz as a confidential informant and contends that, because of that relationship and the absence of any warnings, the Commonwealth failed to satisfy the requirement that it prove beyond a reasonable doubt, see Commonwealth v. Tavares, 385 Mass. 140, 152, cert. denied, 457 U.S. 1137, (1982), that the statement was voluntary.
The defendant points to the evidence that the meeting was arranged by the officer with whom he had been cooperating, that nothing was said to indicate that the discussion was not confidential, and that no mention was made that he was a target of the investigation. Failure of the detectives to warn him that he might be charged with the crime they were investigating and that any statements he might make could be used to convict him of that crime, he maintains, was, in the circumstances, so deceptive as to make the statement involuntary. See Commonwealth v. Dustin, 373 Mass. 612, 615-616 (1977), cert. denied, 435 U.S. 943 (1978); Commonwealth v. Meehan, 377 Mass. 552, 563 (1979), cert. dismissed, 445 U.S. 39 (1980); Commonwealth v. Nero, 14 Mass. App. Ct. 714, 717 (1982); Commonwealth v. Chandler, 29 Mass. App. Ct. 571, 576-577 (1990); United States v. Rogers, 906 F.2d 189, 192 (5th Cir. 1990). But see Commonwealth v. Wills, 398 Mass. 768, 777 (1986) (suspect need not be advised of his status as such before his statement may be considered voluntary).
We are aware of no decision, and the defendant does not point us to any, holding that the relationship between the po*33lice and a confidential informant guarantees that incriminatory statements made in the course of the relationship may not be used to convict the informant of the crime being investigated. There was no evidence that the police made a deal with the defendant, or that he was intentionally misled. See Illinois v. Perkins, 496 U.S. 292, 297 (1990). There may well be a situation so misleading to an informant that he would reasonably believe that he has nothing to fear from making an incriminatory statement about the crime; such a statement might not meet the test of voluntariness. This, however, is not such a situation. The officers stated their purpose at the outset: to question the defendant about the Beverly bank robbery. They were from a different police department than Sergeant Urbanowicz, and the defendant had never met with them previously. There is no indication that the officers said or did anything to create the impression that they would regard the information the defendant provided as confidential and that they would not use the defendant’s statements to prosecute him for the crime. Contrast United States v. Rogers, 906 F.2d at 191. It was not error, therefore, for the motion to suppress the statement to be denied.
2. The second statement. After they left the defendant’s home midday on Friday, the Beverly police officers showed the defendant’s photograph to two tellers who were in the bank at the time of the robbery. They made positive identifications. Later the same day, Detective Bianchi called the defendant to inform him that his photograph had been selected and asked him to come to the Beverly police station. The defendant arrived in the evening with his wife and a child. He was given his Miranda warnings and placed under arrest. He indicated to the officers that he had been aware all along that he was a suspect. He expressed his fear of the other participants, at least one of whom was being held in jail, and he discussed his need for protective custody, bail, and the possibility of a disposition not involving incarceration. When the defendant asked how he could have been identified if masked, the detectives told him he had been seen going into the bank. The defendant replied by shaking his head and *34commenting as an acknowledgement, “Seen going into the bank.”
The defendant contends that his arrest was unlawful and that the statement should have been suppressed as a product of the unlawful arrest. He bases his claim on the alleged constitutional violations committed in the course of the morning interview. We have decided, however, that there were no such violations. The officers had probable cause to arrest the defendant once his photograph, taken with his consent, had been identified by the tellers, and the Miranda warnings were given before he made the statement in issue. Denial of the suppression motion was not error.
3. The third statement. When asked at the Beverly police station on Friday evening after his arrest if he wanted to cooperate further, the defendant asked for the weekend to think about it. He was unable to raise the required bail and was kept in police lockup over the weekend. On Monday morning, Detective Bianchi approached the defendant and, without repeating the Miranda warnings, asked him if he had decided whether to cooperate. The defendant responded that “he wanted a little more time to think about it.” Detective Bianchi proceeded immediately to discuss protective custody. Then he said, “[W]e would at least like to get the gun back.” The defendant replied with the third statement in issue to the effect that they already had the gun, as it was the same gun they had taken from an individual arrested for another robbery.1
The defendant moved to suppress the statement on the ground that it was the product of interrogation conducted by the police after he had expressed his desire to remain silent and without the benefit of a new set of Miranda warnings. The judge found “beyond a reasonable doubt” that the statement was made “voluntarily and after the Miranda warning was given two days earlier.” On appeal, the defendant contends that he had expressed his desire to cut off questioning *35and that his wish to remain silent had not been “scrupulously honored.” See Michigan v. Mosley, 423 U.S. 96, 104 (1975).
In light of the fact that on Monday morning, after saying he wanted more time to consider whether to cooperate, the defendant discussed his predicament with the officers in a sophisticated manner and did not hesitate to answer the question about the gun,2 had the Miranda warnings been repeated, suppression would not have been required. See Commonwealth v. Gallant, 381 Mass. 465, 466 (1980); Commonwealth v. Bradshaw, 385 Mass. 244, 265-266 (1982); Commonwealth v. Westmoreland, 388 Mass. 269, 278 (1983); Commonwealth v. Pennellatore, 392 Mass. 382, 387-388 (1984). We think it dispositive of the claim, however, that a new set of Miranda warnings was not given. Miranda warnings, once given, “are not to be accorded unlimited efficacy or perpetuity.” Commonwealth v. Cruz, 373 Mass. 676, 687 (1977), quoting from United States v. Hopkins, 433 F.2d 1041, 1045 (5th Cir. 1970), cert. denied, 401 U.S. 1013 (1971). The original warnings, on Friday evening, were insufficient to carry over to the interrogation by Detective Bianchi on Monday morning, see Commonwealth v. Coplin, 34 Mass. App. Ct. 478, 483 (1993), and the period between the warning and the resumption of interrogation exceeded by far those time lapses which have been found insignificant for purposes of determining the validity of the defendant’s knowing, voluntary, and intelligent waiver of his rights. See Commonwealth v. Cruz, 373 Mass. at 685-687 & n.6 (three hours); Commonwealth v. Silva, 388 Mass. 495, 502 (1983) (three hours); Commonwealth v. Harris, 11 Mass. App. Ct. 165, 174 (1981) (less than one and one-half hours). But see Commonwealth v. Sousa, 350 Mass. 591, 598 (1966) (eighteen hours). In the circumstances here, including both the lapse of a considerable period of time and the defendant’s expression of his wish for more time before deciding whether to cooperate, the Miranda warnings should have been repeated before he was questioned further by the *36police. Absent the warnings, there was no showing of a knowing, voluntary, and intelligent waiver, and the statement should have been suppressed. See Commonwealth v. Murray, 359 Mass. 541, 544-546 (1971) (lapse of two days between warning and interrogation not sufficient to establish waiver).
We conclude, however, that the error with regard to the third statement, that the officers had the gun because it was one used in another robbery, was harmless beyond a reasonable doubt. See Commonwealth v. Marquetty, 28 Mass. App. Ct. 690, 696 (1990). The statement was not an admission of the defendant’s participation in the robbery, but it did tend to incriminate him as it indicated that he had detailed knowledge about the robbery. However, numerous other statements of his, properly admitted, revealed that he possessed very detailed knowledge of the robbery, including the identity of the participants, how the getaway vehicle was obtained, and where the red-dye soaked money was taken to be cleaned. Moreover, the other evidence of the defendant’s guilt was substantial. Apart from the defendant’s numerous inculpatory statements, properly admitted, two eyewitnesses identified the defendant’s photograph and one identified him in court.3
Judgment affirmed.