the Metropolitan Police Department, testified that on July 7, 1970, at approximately 11:30 P.M., he and Officer Martin Holland, both in plain clothes, observed appellant and a companion seated on a curb by a "carry-out" restaurant at 1164 Bladensburg Road, N.E. Blackburn said he approached them and asked appellant if he knew where "John" lived, and received a negative answer. As the officers walked away, appellant and his companion then rose, and, after pointing in the officers' direction, proceeded toward Bladensburg Road. The officers followed and, almost immediately thereafter, saw appellant drop something from his right hand.
Blackburn, testifying that he was within 10 feet of appellant when he saw him drop something, and that he never lost sight of what had been dropped, went over to the spotand recovered a syringe, a needle, and a soda bottle top with a sooty, black smudge on the bottom  all within 18 inches of one another. An expert witness from the Narcotics Squad explained how the particular items could be used to administer heroin, and a chemist testified that his qualitative analysis disclosed no traces of narcotics in the syringe or needle but did reveal heroin traces in the bottle top. No further evidence was presented by the prosecution.
Appellant testified that on the evening in question he had been playing basketball in the neighborhood and was indeed sitting on the curb when he was approached by a stranger who asked if he knew where "John" lived. He stated that he and his companion were arrested just after