Ordered that the judgment is affirmed, with costs.
It is well settled that the decision whether to prosecute is entrusted to the sole discretion of the District Attorney (see Matter of Nieblas v Kings County Dist. Attorney, 209 AD2d 703; Matter of Hynes v Demurest, 202 AD2d 669; see also People v Di Falco, 44 NY2d 482). Mandamus cannot be used to compel a purely discretionary act by a public official ( see Matter of Mullen v Axelrod, 74 NY2d 580; Matter of Milek v Town of Hempstead, 294 AD2d 440). Accordingly, the dismissal of the proceeding was proper.
The petitioner's remaining contentions are raised for the first time on appeal, and are thus not properly before this Court.