Can a federal prosecutor pursue criminal charges against a defendant who has already been convicted in a state trial?

A federal prosecutor may, in deciding whether to pursue a subsequent prosecution, take into consideration what he deems an "inadequate result" obtained in the state trial. United States v. Ng, 699 F.2d 63, 68 (2d Cir.1983). The fact that the federal government as a matter of policy does not routinely pursue criminal charges against a defendant who has already been convicted in state court, see, e.g., Petite v. United States, 361 U.S. 529, 530-31, 80 S.Ct. 450, 4 L.Ed.2d 490 (1960) (per curiam), in no way prevents the federal government from doing so whenever it considers that the state proceeding has failed adequately to protect a federal interest, see, e.g., United States v. Davis, 906 F.2d 829, 832 (2d Cir.1990).