OPINION OF THE COURT
Lawrence, J. The question to be decided on this appeal is whether the defendant is entitled to a new trial on the ground that the prosecution violated his right to due process by withholding specifically requested Brady material from the defense (see, Brady v Maryland, 373 US 83). In our view, this question must be answered in the affirmative.
In a two-count indictment, the defendant was charged with criminal possession of a controlled substance in the fourth and seventh degrees, arising out of events which allegedly occurred on November 24, 1989. At the Mapp hearing, held on March 19, 1990, immediately prior to jury selection which commenced on the same day, the arresting officer’s testimony disclosed the theory of the prosecution, linking the defendant’s arrest to a so-called "buy-and-bust” operation.
The officer testified that on November 24, 1989, he was assigned to the Queens Tactical Narcotics Task Force as part of the "back-up team” supporting the buy-and-bust operation. *134He received a radio report from an undercover officer reporting that a purchase had been made in the vicinity of a certain intersection together with a description of the seller, and drove to that intersection. He spotted the defendant standing alongside a store on the corner. He testified that he watched as the defendant turned to face him and then entered a store.
The prosecutor specifically inquired of the officer:
"Q. Now, before he turned and walked away from you was there a reason that you were observing him?
"A. The transmission I received from an undercover officer was similar to the description of Mr. Clausell on that day”.
The officer testified that after the defendant entered the store, he observed the defendant "through the plateglass window on the side of the store”, removing some tinfoil packets and dropping them to the floor. The officer then exited his car, entered the store, recovered four tinfoil packets from the floor, and arrested the defendant.
On cross-examination, the officer made it clear that the reason he observed the defendant was that defendant "fit the description” of the seller. The officer testified that the description he received was "Male, Black, blue coat and a sweatshirt”. He also testified there was no description as to facial features or as to age and that he could not recall any description as to the seller’s height.
The record establishes that following the suppression hearing and prior to opening statements, the defense counsel specifically requested production of the "buy report” and the accompanying "buy corroboration report”. Moreover, the trial court ordered the prosecutor to inquire as to the existence of the reports and to produce them. The prosecutor reported back to the court that those reports did not exist.
At the trial, the officer was again asked by the prosecutor on the People’s direct case, what drew his attention to the defendant. The officer reiterated: "He fit the description or matched, if you will, the description of an individual we were looking for in reference to the narcotics transaction”. On cross-examination at trial, the officer emphasized, "My eyes were strictly on him”. "He fit the description of the person we were looking for”.
On March 22, 1990, after the arresting officer had concluded his testimony, the defense counsel complained again to the court that the buy report had not been produced. The court again ordered the prosecutor to produce the report, noting *135that "[t]here must be some record of the money”. When the prosecutor reported once more that there was no buy report, the defense counsel obtained a subpoena duces tecum, directed to the Queens Narcotics Division of the Police Department, for the production of "any and all reports, in particular, buy report pertaining to the [subject] buy”. The subpoena was served on March 23, 1990, returnable March 26, 1990.
The buy report was not produced until April 5, 1990, nine days after the defendant’s conviction. It revealed, as the trial court found, that the undercover officer’s description of the seller "was wholly at odds with the testimony given by [the arresting officer]”. The undercover officer referred to the seller as "JD Leather” and described him as approximately 35 years in age, six feet tall, weighing 185 pounds, and wearing a gray cloth coat and black leather pants. The arresting officer had testified that the defendant was wearing a "blue coat and a sweatshirt”. Moreover, the record discloses that the defendant was 5 feet 3 inches tall and 27 years of age at the time of his arrest.
Under these circumstances, we agree with the trial court’s determination that the defendant is entitled to a new trial. Initially, it is worth noting what is not in dispute. The dissent acknowledges that "[wjhere the defense itself has provided specific notice of its interest in particular material, heightened rather than lessened prosecutorial care is appropriate” (People v Vilardi, 76 NY2d 67, 77). Indeed, the Court of Appeals has found the "prosecution’s failure to turn over specifically requested evidence to be 'seldom, if ever, excusable’ and to verge on prosecutorial misconduct” (People v Vilardi, supra, at 74; quoting from People v Brown, 67 NY2d 555, 559; United States v Agurs, 427 US 97, 106). Thus, where, as here, the prosecutor was made aware by a specific discovery request that the defendant considered the material important to the defense, the appropriate standard is whether there is a " 'reasonable possibility’ that the failure to disclose the exculpatory report contributed to the verdict” (People v Vilardi, supra, at 77).
In addition, the dissent recognizes the rule that where "the outcome of a case turns on the credibility of the complaining witness, evidence impacting adversely on [his] credibility constitutes Brady material (see, People v Cwikla, 46 NY2d 434)” (People v Janota, 181 AD2d 932, 934). However, we do not agree with the dissenter’s position that the buy report was not a material impeachment device, since it only concerned "col*136lateral” matters, and that consequently the failure to disclose it did not contribute to the verdict.
As already noted, it was the prosecutor who introduced the evidence, both at the hearing and at trial, that the arresting officer responded to the scene and focused on the defendant, because an undercover officer had provided a description of a seller which allegedly matched the appearance of the defendant. Clearly, the People believed it was necessary to explain why the arresting officer’s attention was drawn to the defendant. In fact, the officer’s testimony in this regard was important in overcoming doubts about his claim that he saw the defendant drop glassine envelopes. The store owner testified that, contrary to the officer’s assertions, there were advertisements on the store window and other obstructions blocking the window. In addition, an investigator testified that when he was positioned at the vantage point reported by the officer he could only see movement of the upper torso of a person’s body inside the store. Had the report been available, the defense counsel would have been able to impeach the officer much more thoroughly about his observations; particularly since his description of the seller was "wholly at odds” with that provided in the report by the undercover officer. The defense counsel might even have elected to call the undercover officer as a witness to establish that the defendant had nothing to do with the drug sale.
Thus, it is readily apparent that the report constituted a "material impeachment device” concerning issues central to a determination of guilt. Moreover, as the trial court observed, the People’s case "depended almost entirely on the testimony of [the arresting officer]” and his "credibility and reliability as the People’s chief witness were important issues in the case”. Since there is a " 'reasonable possibility’ that the failure to disclose the exculpatory report contributed to the verdict” (People v Vilardi, supra, at 77), we find that the trial court correctly determined that the defendant is entitled to a new trial (see, People v Cwikla 46 NY2d 434, 441, supra).
Finally, we note that on the People’s appeal we cannot reach the question of whether the evidence was legally or factually sufficient. The parties have not briefed these issues. Moreover, by law the Appellate Division’s review is limited to "any question of law or issue of fact involving error or defect in the criminal court proceedings which may have adversely affected the appellant” (CPL 470.15 [1] [emphasis added]). Since this is an appeal by the People, consideration of the *137sufficiency of the evidence must await a direct appeal by the defendant if, after the new trial, he is again convicted and sentenced (see, People v Karp, 76 NY2d 1006; People v Good-friend, 64 NY2d 695).