Appeal by the People from an order of the Supreme Court, Kings County, dated November 19, 1979, which granted defendant’s motion to dismiss his indictment, in the interest of justice. Order affirmed. A promise of leniency was made to the defendant by law enforcement officials to gain his co-operation in a pending unrelated criminal investigation. Accordingly, defendant performed valuable services which exposed him to great danger. Under these circumstances, the dismissal of the indictment *836was an appropriate exercise of the trial court’s discretion (see People v Argentine, 71 AD2d 869). Although the agreed services were not completely performed, the failure to adequately protect the defendant from the threats of the target of the investigation excused further performance. The failure to enforce the District Attorney’s promise would do substantial injustice, not only to the defendant but to the public which is entitled to have the benefit of future co-operation (see Matter ofChaipis v State Liq. Auth., 44 NY2d 57, 65). Gibbons, J. P., Rabin, Gulotta and Margett, JJ., concur.