The law does not look kindly on those who commit perjury or withhold evidence.
18 U.S.C. § 1512. Tampering ...
(c) Whoever corruptly
(1) alters, destroys, mutilates, or conceals a record, document, or other object, or attempts to do so, with the intent to impair the object’s integrity or availability for use in an official proceeding; or
(2) otherwise obstructs, influences, or impedes any official proceeding, or attempts to do so,
shall be fined under this title or imprisoned not more than 20 years, or both.
(i) A prosecution under this section or section 1503 may be brought in the district in which the official proceeding (whether or not pending or about to be instituted) was intended to be affected or in the district in which the conduct constituting the alleged offense occurred.
(j) If the offense under this section occurs in connection with a trial of a criminal case, the maximum term of imprisonment which may be imposed for the offense shall be the higher of that otherwise provided by law or the maximum term that could have been imposed for any offense charged in such case.
(k) Whoever conspires to commit any offense under this section shall be subject to the same penalties as those prescribed for the offense the commission of which was the object of the conspiracy.