18 U.S.C. § 551: Concealing or destroying invoices or other papers

Whoever willfully conceals or destroys any invoice, book, or paper relating to any merchandise imported into the United States, after an inspection thereof has been demanded by the collector of any collection district; or Whoever conceals or destroys at any time any such invoice, book, or paper for the purpose of suppressing any evidence of fraud therein contained— Shall be fined under this title or imprisoned not more than two years, or both.