18 U.S.C. § 1505 : US Code - Section 1505: Obstruction of proceedings before departments, agencies, and committees

      Whoever, with intent to avoid, evade, prevent, or obstruct
    compliance, in whole or in part, with any civil investigative
    demand duly and properly made under the Antitrust Civil Process
    Act, willfully withholds, misrepresents, removes from any place,
    conceals, covers up, destroys, mutilates, alters, or by other means
    falsifies any documentary material, answers to written
    interrogatories, or oral testimony, which is the subject of such
    demand; or attempts to do so or solicits another to do so; or
      Whoever corruptly, or by threats or force, or by any threatening
    letter or communication influences, obstructs, or impedes or
    endeavors to influence, obstruct, or impede the due and proper
    administration of the law under which any pending proceeding is
    being had before any department or agency of the United States, or
    the due and proper exercise of the power of inquiry under which any
    inquiry or investigation is being had by either House, or any
    committee of either House or any joint committee of the Congress - 
      Shall be fined under this title, imprisoned not more than 5 years
    or, if the offense involves international or domestic terrorism (as
    defined in section 2331), imprisoned not more than 8 years, or
    both.