(concurring in part, dissenting in part). 1. Motion to suppress. I agree with the majority that the police possessed probable cause to arrest, having interrupted what they appropriately perceived as a drug deal in progress.
2. Improper cross-examination. Even assuming that the single question concerning Drayton having been convicted of heroin distribution was inappropriate,1 it is difficult to ascertain any prejudice. Drayton was the middleman in a drug transaction. Indeed, this fact helped establish probable cause to arrest. The jury, having heard of her involvement in selling heroin, could not have been adversely affected by a single question concerning the same general subject matter. Further, the response to the question was in the negative. In his final instructions, as in his preliminary instructions, the judge properly instructed the jury that such questions are not evidence.2 Lastly, the jury’s acquittal *298of the defendant on the two serious charges demonstrates their ability to assess properly the evidence.
3. Factual misstatements in closing. The defendant testified to a somewhat implausible story — a self-employed mechanic, driving around, late at night, at approximately 11:40 p.m., taking the car he is allegedly working on for a test ride, when he happens to bump into Wanda Drayton, out walking, whom he agrees to drive home. Just as he was pulling up to drop Drayton off, the police happen to stop him, search the car and surprisingly find fifty bags of heroin and money under the seat. A defense witness testified that she had hired him to fix her car,3 which belonged to her husband who was, at the time of the incident, incarcerated for a “drug case” involving heroin.
A prosecutor can remark on the defendant’s theory of the case, as long as the statements and inferences are based in evidence and do not represent the prosecutor’s personal beliefs on the credibility of the defendant. See Commonwealth v. Bradshaw, 385 Mass. 244, 272 (1982); Commonwealth v. Sleeper, 435 Mass. 581, 595 (2002). Where a defendant testifies, a prosecutor can properly refer to the defendant’s lies. See ibid. (based in part on theory that defendant’s testimony was preposterous, prosecutor’s reference to defendant’s lies was proper). Additionally, “[i]t is not improper for the prosecutor to suggest to the jury that the defendant attempted to ‘fool’ them.” Commonwealth v. Cohen, 412 Mass. 375, 388 (1992). Nor is there “error in permitting the prosecutor to argue that the defense was contrived. The question of credibility of the witness was fundamental to the trial.” Commonwealth v. Cameron, 385 Mass. 660, 669 (1982).
The prosecutor handled with skepticism, properly I submit, the tale spun by the testifying defendant. The prosecutor stated, in part:
“Think of the circumstances that he tells you about. He just so happens to go over to a drug dealer’s house to fix *299the drug dealer’s car. And then he drives around and he picks up a woman. And lo and behold, who is that woman? And what does she do for a living? Is she involved in the drug trade? And lo and behold they stop at 32 Maple Street, and who approaches the car? Someone the officers know to be involved in heroin.
“So this poor guy, three times in one night, is surrounded by heroin users and drug dealers. And he wants you to believe it’s all circumstance. 11:40 p.m. on a work night and all of a sudden all his friends are either heroin users or heroin dealers. And it’s a circumstance. Do you believe it?”4
While the majority finds neither evidence nor permissible inferences to support the prosecutor’s closing, both are clearly evident. Wanda Drayton, who was involved in the drug sale which helped create probable cause to arrest, is a drug dealer.5 The person approaching the car, who passed money to Drayton, ostensibly to purchase the drugs, is a drug buyer.6 The car’s owner, as testified to by the defense, was at the time, serving a sentence for a “drug case” involving heroin. As fifty packets of heroin were found in the car and no other drug, it is permissible to infer that the drug dealers were heroin dealers and the drug purchaser was a heroin buyer. The prosecutor’s closing on this point was permissible. To conclude that “[t]he prosecutor’s quoted statements were devoid of evidentiary basis in every material respect” is simply wrong.
Moreover, the jury were instructed, both at the preliminary and final stages, that the closing arguments of counsel were not to be considered as evidence, which minimized any possible *300prejudicial effect.7 See Commonwealth v. Ortiz-Soto, 49 Mass. App. Ct. 645, 650 (2000).
4. Improper vouching. The police testified that, as they approached the car from the front, the defendant made a gesture as if placing something under the seat, which when searched revealed fifty bags of heroin and $184. The defendant asserted that he did not make the gesture. The defendant, in his closing, intimated that the police were being less than candid.8
In response, the prosecutor, in his closing, characterized this argument as calling the police liars.9 The defendant, although vigilant and objecting to other evidence, chose not to object *301here. The majority characterizes this unobjected-to argument as prosecutorial vouching.
“Improper vouching can occur if an attorney expresses a personal belief in the credibility of a witness, or indicates that he or she has knowledge independent of the evidence before the jury.” Commonwealth v. Wilson, 427 Mass. 336, 352 (1998).
Here the prosecutor did not vouch for the credibility of the police officers. There was no expression of personal belief in the credibility of the police or an indication that the prosecutor had knowledge independent of the evidence before the jury. The prosecutor simply made an accurate statement of fact: that if the jury believed the defendant, they could not also believe the police. It is axiomatic that when there are two conflicting versions of events and one side is found, by a jury, to be true, the other side has to have been found to be not true.10 “In a case that essentially reduces to which of two conflicting stories is true, it may be reasonable to infer, and hence to argue, that one of the two sides is lying.” Commonwealth v. Murchison, 418 Mass. 58, 60 (1994), quoting from United States v. Molina, 934 F.2d 1440, 1445 (9th Cir. 1991).
5. Conclusion. A defendant is entitled to a fair trial, not one free from all error. While missteps were made here, including some aspects of the prosecutor’s closing argument, none resulted in the defendant receiving anything other than the trial to which he was entitled. That the jury were intelligent and sophisticated, moving beyond puffery and rhetoric, is evidenced by their finding the defendant not guilty of the serious charges facing him (drag trafficking in a school zone) and finding him guilty only of so much of the first indictment as alleged simple possession. That militates, in part, against finding both prejudicial error and a substantial risk of a miscarriage of justice. As such, I respectfully dissent.
It appears the question was asked, not to disparage the defendant’s character as the majority indicates, but rather to shed light on the knowledge element of the crime. See Commonwealth v. Supplee, 45 Mass. App. Ct. 265, 268 (1998) (“We do not discount the possibility that a case might arise in which a judge, within discretion, could permit the use of someone else’s conviction in cross-examination to test the accuracy of a witness’s perception”). See also Commonwealth v. Robinson, 43 Mass. App. Ct. 257, 260-261 (1997).
The majority characterizes the jury instruction as “tardy and tepid” and “standard, not curative.” How then does a jury respond to such an instrac*298tian? Are they not, as we have written countless times, presumed to follow the instructions given them? See Commonwealth v. Pope, 406 Mass. 581, 588 (1990).
She testified that the car was either a white Chevrolet or a Plymouth Reliant. The police officers testified that the car was a yellow Ford Fairmont.
Other eyebrow-raising aspects of the defense involved (1) his driving with a suspended operator’s license; (2) his testimony of calling his wife at approximately 8:30 p.m. to let her know that he would be home in a little while, yet taking the car for a forty-five minute test drive on the highway and being arrested at nearly midnight; and (3) the logic of one in jail for a heroin-related charge leaving $184 and fifty bags of heroin underneath the driver’s seat in his car for six weeks.
The middleman in a drug deal is a drug dealer. That Drayton that evening was acting in such a capacity permitted the prosecutor to refer to her as one.
There was also evidence, developed during the cross-examination of one of the arresting officers, that the person who approached the car was a “drug abuser.”
Once again, the majority gives short shrift to the jury instruction, characterizing it as “minimally standard.” See note 2, supra.
“Officer Jones says, I saw his shoulder dip. No doubt. I saw his shoulder dip as I was approaching the car from twenty feet. Just — on February 10, 2000, a couple of months ago, I asked him, Did you see his shoulder — Did ■ you see him lean down? And if you remember, I had him read his own statement, which he reviewed for some time, to confirm. And he read it to you. A couple of months ago, he wasn’t so sure, he says — and that was at a hearing before a judge, under oath — ‘I guess, I guess he would have to lean down slightly.’
“That has now progressed to, I saw his shoulder dipping.
“And just think about what the officers said about where he found the drugs; under the center of the seat.
“We’ve all been in cars before. I would just leave it up to you to see if it makes sense that someone who sees somebody approaching would be able to put drugs under the center of the seat in that instant.
“They’re making a mountain out of a molehill because they have nothing to connect [the defendant] with the drugs. They’re asking you to make a leap from leaning down, shoulder dip, to yes, he did possess the drugs and he was distributing drugs.”
The prosecutor argued, in part, and in part excessively: “Ladies and gentlemen of the jury, what you just heard from [defense counsel] as he politely — what he was doing — and I grant you he was doing it very politely — he was just calling somebody a liar. Because, you see, you can’t have it both ways. He’s not saying they were mistaken. He’s saying those two police officers, with a combined twenty-six years of experience in the various neighborhoods protecting the streets of the City of Boston, came in here, walked up to that stand, took the oath, and lied. That’s what he’s saying. They came in here and lied.”
The prosecutor later asserted, arguably coming close to, if not stepping over the line, “Again, [if] you believe them, you’re calling those two police officers liars. That’s the fact of the matter.”
Some cases, of course, may call into question the possibility of a good faith mistake being made, as opposed to a lie. As veteran trial counsel know, it is rare to call a witness a liar, preferring the more subtle route. A trial judge must listen closely to ensure that the arguments made are warranted by the evidence.