42 U.S.C. § 1987: Prosecution of violation of certain laws

The United States attorneys, marshals, and deputy marshals, the United States magistrate judges appointed by the district and territorial courts, with power to arrest, imprison, or bail offenders, and every other officer who is especially empowered by the President, are authorized and required, at the expense of the United States, to institute prosecutions against all persons violating any of the provisions of section 1990 of this title or of sections 5506 to 5516 and 5518 to 5532 of the Revised Statutes, and to cause such persons to be arrested, and imprisoned or bailed, for trial before the court of the United States or the territorial court having cognizance of the offense.