— Appeal from a judgment of the County Court of Schenectady County, rendered January 21, 1974, upon a verdict convicting defendant of the crime of criminally selling a dangerous drug in the third degree. The jury has found defendant guilty of selling heroin to an undercover agent investigating traffic in narcotics. The only issue of substance on this appeal concerns the chain of possession of the contraband material from the time it was obtained from the defendant until its ultimate introduction into evidence at the trial. The investigating officer testified he recognized the exhibit, a glassine bag containing a white powder, as being the same package he had obtained in the course of his dealings with the defendant and which he had marked upon receipt with the date and his
