18 U.S.C. § 4 : US Code - Section 4: Misprision of felony

      Whoever, having knowledge of the actual commission of a felony
    cognizable by a court of the United States, conceals and does not
    as soon as possible make known the same to some judge or other
    person in civil or military authority under the United States,
    shall be fined under this title or imprisoned not more than three
    years, or both.