(dissenting, with whom Lenk, J., joins). Com*481monwealth v. Sykes, 449 Mass. 308 (2007), was acknowledged to be a “close case” on its considerably more compelling facts. Id. at 314. The majority in my view misconstrues the very limited factual record that is before us, fails to accord significance to the many respects in which this case differs from Sykes, and misapplies the teachings of Sykes. Accordingly, I respectfully dissent.
Facts matter, perhaps nowhere more than in situations involving the suppression of evidence recovered by police following what is said to have been an unlawful seizure. Determining whether and when a seizure occurred is critical, for a seizure is an intrusion of constitutional dimensions that the Commonwealth must justify. Id. at 310-311. See Commonwealth v. Thinh Van Cao, 419 Mass. 383, 387, cert. denied, 515 U.S. 1146 (1995). The motion judge here made succinct findings of fact, reproduced in their entirety below,1 after concluding an evidentiaiy suppression hearing at which the Commonwealth bore the burden of proof. See Commonwealth v. DePeiza, 449 Mass. 367, 369 *482(2007). We know that those findings reflect all that the judge found believable because he stated in no uncertain terms that “any other testimony is specifically not credited by the court.”
The Commonwealth as appellant, for reasons best known to itself, has not provided a transcript of the hearing. See Mass. R.A.P. 8, as amended, 430 Mass. 1601 (1999). The Commonwealth accordingly cannot contend that any of the judge’s findings of fact are erroneous, and we must accept them in their entirety, reviewing independently only the “correctness of the judge’s application of constitutional principles to the facts as found.” Commonwealth v. Scott, 440 Mass. 642, 646 (2004), quoting from Commonwealth v. Mercado, 422 Mass. 367, 369 (1996). Because the transcript has not been provided, we may not supplement the judge’s findings with uncontested evidence from the motion hearing.2 Compare Commonwealth v. Costa, 448 Mass. 510, 512 n.3 (2007); Commonwealth v. Correia, 66 Mass. App. Ct. 174, 175-176 (2006), citing Commonwealth v. Kitchings, 40 Mass. App. Ct. 591, 593 n.4 (1996). In these circumstances, I see no reason to construe the facts found by the judge in the light most favorable to the Commonwealth, as the majority appears to do. That being said, I turn to the aspects of the majority’s analysis that I think are mistaken.
*4831. When did the seizure occur? The court in Sykes instructs that “[determining the precise moment at which a seizure occurs is critical to resolving the issue of suppression.” Commonwealth v. Sykes, 449 Mass. at 310. The judge here found that the police, who had been following the defendant in their unmarked car as he rode his bicycle, “jumped out of the cruiser and ran after him” when he dropped his bicycle and started to run. Sykes quite plainly instructs that “for constitutional purposes [the defendant’s seizure] occurred when the officers left their cruiser and began to chase the defendant” (emphasis added). Id. at 314. In this case, the defendant discarded his gun well after the chase began, i.e., after he was seized, for constitutional purposes. The “precise moment” in this case is the same as in Sykes. The majority’s analysis fails to specify the moment of seizure. They focus instead both on the “time [the defendant] discarded his firearm” and on the defendant’s actions (“no stop in the constitutional sense occurred before the defendant abandoned his bicycle and began to run”), rather than on the action of the police. This lack of specificity and misplaced focus are not helpful to a simple Sykes analysis, tending instead to blur the facts that distinguish this case from Sykes.
2. Justification for the seizure. On the issue of reasonable and articulable suspicion to validate the defendant’s seizure, the majority contends that reversal is required by Sykes, asserting that the facts in Sykes are indistinguishable in any material respect from the facts as they discern them here. I disagree. On the facts that the judge found, Sykes requires suppression of the evidence.
In Commonwealth v. Sykes, 449 Mass. at 309, the police officers observed the defendant in a high crime area as he was separating himself from a group of black and Hispanic males who had been reported to the police as engaging in drug activity.3 In stark contrast, in this case, there are no facts of record and no findings that the defendant was connected to criminal activity, that he was part of a group so engaged, or even that he was *484in a high crime area. Indeed, the judge found that the three “officers were talking with four males known to them for ‘firearm related incidents’ ” and that the defendant, “a black male on a bike,” “was not the subject of any discussion with the four males” before one of the four males “ma[d]e some sort of hand gesture” to the defendant and the defendant rode away on his bicycle. The record is silent as to the defendant’s relationship, if any, with the four males. The otherwise undescribed “some sort of hand gesture” suggests that one of the four knew the defendant. That man walked away from police and the other three men who were speaking with the police, after he gestured to the defendant. The defendant turned around and bicycled away from the remaining group. We know no more than this, and will not read into it, as the majority does, anything more than that one man did not join the group, and that one man left it. We do not know why.
The majority’s recitation that the officers in this case were “questioning . . . four individuals known for criminal activity involving firearms” (emphasis added) amounts to appellate fact-finding because nothing in the record supports any such “criminal activity.”
In Commonwealth v. Sykes, 449 Mass. at 309, the police officers, even though in plain clothes, wore shirts “emblazoned with the words ‘Boston Police Department Anti-Crime Unit,’ and all four officers were displaying their badges outside of their clothes.” Hence, it was reasonable to infer that the defendant in Sykes, who looked at his pursuers several times as he rode away, knew that the individuals who were surveilling him and asking to speak with him were police officers and, therefore, that his subsequent actions were taken for the purpose of avoiding the police.4 Here, there is no finding that the defendant looked back at his pursuers as he rode away. Rather, there is a finding that, when the pursuers pulled up next to him and said, “What’s up, can we talk to you,” he had a panicked look. *485There is no finding that he knew that his pursuers were police officers. The judge found that the officers were “plain-clothed” and in an “unmarked” car. Nothing in the findings tells us anything more about the police officers or their appearance. There is, therefore, no basis for concluding as the majority does that the defendant was attempting to avoid contact with the police. The judge, of course, made no such finding. In my view the majority’s reasoning, which is based upon an impermissible inference that the defendant knew that his pursuers were police officers, is flawed.5
Finally, in Sykes, the defendant was observed clenching his waistband prior to the seizure, i.e., when the four police officers left their vehicle and began the chase. However, in this case, the officers jumped out of the cruiser and began their chase before Officer Tarrantino saw the defendant pulling at his waistband and then observed what looked like the handle of a gun.6 It is impermissible to use Officer Tarrantino’s postseizure observation of the defendant clutching his waistband in order to justify a seizure that had already occurred without the benefit of that observation. See Commonwealth v. Scott, 52 Mass. App. Ct. 486, 492-496 (2001).
The court in Commonwealth v. Sykes, 449 Mass. at 314, acknowledged that, even on its facts, it was a close case. In my view this case, on the facts found by the judge, is clearly on the other side of the line. I would accordingly affirm the judge’s grant of the defendant’s motion to suppress.
"FINDINGS OF FACT
“On May 28, 2006, boston [rie] police officers Cogavin, Cooley and Tarantino observed a black male on a bike crossing over Morton to Wildwood Street. At that time, the officers were talking with four males known to them for ‘firearm related incidents.’ The man on the bike, [the defendant], was not the subject of any discussion with the four males. Cooley saw one of the males they were talking to look at [the defendant] and make some sort of hand gesture to [the defendant] and then walk away from [the defendant], the three other males and the police. Cooley saw [the defendant] turn around and peddle [s/e] his bike away from the four males and three plain-clothed police officers.
“The three police officers entered their unmarked police car without lights or a siren and followed [the defendant], who was riding his bike. The driver pulled the unmarked cruiser beside [the defendant] and Cooley said ‘What’s up, can we talk to you?’ [The defendant] had a panicked look. The officers had no information from any source supporting a conclusion that [the defendant] had committed a crime, was committing a crime or was about to commit a crime. [The defendant] got ahead of the cruiser. At that point, [the defendant] dropped his bike and started to run. The officers jumped out of the cruiser and ran after him. Tarrantino as he ran after [the defendant] saw [the defendant] pulling at his waist band and then saw what looked like the handle of a gun. Tarrantino called out to his partners ‘He’s got a gun,’ and continued running after [the defendant]. He saw [the defendant] throw the gun onto a roof. Cooley caught [the defendant], took him to the ground at *482which point he was handcuffed. A gun was found on the roof where [the defendant] had thrown it.”
“Appellate courts may supplement a judge’s finding of facts if the evidence is uncontroverted and undisputed and where the judge explicitly or implicitly credited the witness’s testimony. Commonwealth v. Alvarado, 423 Mass. 266, 268 n.2 (1996). Commonwealth v. Santiago, 410 Mass. 737, 738 n.2 (1991). See Commonwealth v. Butler, 423 Mass. 517, 526 n.10 (1996) (appellate court considers uncontroverted testimony that ‘in no way contradicts] the motion judge’s findings [but] merely fill[s] out the narrative’); Commonwealth v. Scott, 52 Mass. App. Ct. 486, 492 (2001), S.C., 57 Mass. App. Ct. 36 (2003) and 440 Mass. 642 (2004) (court’s willingness to supplement motion judge’s findings based on confidence that material ‘is indeed uncontroverted’ and that motion judge ‘explicitly or implicitly credited the witness’s testimony’). In addition, ‘[o]n a motion to suppress, “[t]he determination of the weight and credibility of the testimony is the function and responsibility of the [motion] judge who saw the witnesses, and not this court.” ’ Commonwealth v. Yesilciman, 406 Mass. 736, 743 (1990), quoting Commonwealth v. Moon, 380 Mass. 751, 756 (1980).”
Commonwealth v. Isaiah I., 448 Mass. 334, 337 (2007).
In Commonwealth v. Sykes, 449 Mass. at 309, the police received the report of current, ongoing criminal activity by way of a 911 telephone call. The factual narrative suggests that the police in Sykes responded with reasonable dispatch to the location of the alleged drug crimes where the defendant in that case was first observed.
The court in Sykes noted as significant the fact that the defendant “made an effort to dodge further contact with the police,” Commonwealth v. Sykes, 449 Mass. at 315 (emphasis added), relying on Commonwealth v. Grandison, 433 Mass. 135, 139-140 (2001), and Commonwealth v. Doocey, 56 Mass. App. Ct. 550, 555-556 (2002), for the proposition that evasive behavior during a police encounter is one factor establishing reasonable suspicion.
Indeed, the police in this case were in plain clothes, using an unmarked car, avoiding lights and sirens, and obviously acting to obscure their identity as police pursuers.
The police observation of the defendant in Sykes “clenching” his waistband, prior to his seizure, and the police observation of the defendant in this case “pulling at his waist band” after the seizure are critical observations in the analysis of reasonable suspicion. See Commonwealth v. DePeiza, 449 Mass. at 368-374 (defendant walking with “straight arm” gait and concealing something from police can contribute to reasonable suspicion).