Appeal by defendant from a judgment of the County Court, Nassau County, rendered March 24, 1972, convicting him of assault in the second degree, upon a jury verdict, and imposing sentence. Judgment affirmed (CPL 470.05, subd. 1). In this case we deplore the comments, made by the prosecutor in summation, that he would not countenance false testimony by a People's witness. In effect, he was skirting the borderline of the cases interdicting the practice of a prosecutor making himself an unsworn witness and supporting his case by his own veracity and position. We also look with disfavor upon an attempt to prove another crime, which the Trial Judge excluded. In view of the lack of exception or request to charge with respect to this incident, and the overwhelming proof of defendant's guilt, we affirm the judgment, but note that overzealousness of this kind may well invalidate convictions in other cases (see, also, People v. Blackman, 43 A.D.2d 742, decided herewith). Latham, Acting P.J., Shapiro, Gulotta, Christ and Benjamin, JJ., concur.