Appeal by the defendant from a judgment of the Supreme Court, Kings County (Pincus, J.), rendered March 21, 1989, convicting him of murder in the second degree, criminal possession of a weapon in the second degree, and escape in the first degree, upon a jury verdict, and imposing sentence.
Ordered that the judgment is affirmed.
The defendant contends that the court improvidently exercised its discretion by allowing the prosecutor to cross-examine the defense witness regarding her failure to come forward to law enforcement officials with the substance of her exculpatory testimony. We disagree. A proper foundation was elicited before the prosecutor commenced this line of questioning (see, People v Dawson, 50 NY2d 311, 322). Moreover, following this questioning the court instructed the jury that this witness was not obligated to come forward (see, People v Payne, 50 NY2d 867; People v Davis, 172 AD2d 553).
*701We also disagree with the defendant’s contention, raised in his supplemental pro se brief, that he was denied a fair trial because of the unavailability of certain Rosario material, since the record fails to demonstrate that this material ever existed.
The defendant’s remaining contentions, including those raised in his supplemental pro se brief, are either without merit or are unpreserved for appellate review (see, CPL 470.05 [2]; People v Nimmons, 72 NY2d 830; People v Shaw, 150 AD2d 626; People v Addison, 174 AD2d 627; People v Suitte, 90 AD2d 80). Eiber, J. P., Rosenblatt, O’Brien and Ritter, JJ., concur.