25 CFR §11.439

1. (a)A person commits a misdemeanor if, believing that an official proceeding or investigation is pending or about to be instituted, he or she attempts to induce or otherwise cause a witness or informant to:
   1. (1)Testify or inform falsely; or
   2. (2)Withhold any testimony, information, document or thing; or
   3. (3)Elude legal process summoning him or her to supply evidence; or
   4. (4)Absent himself or herself from any proceeding or investigation to which he or she has been legally summoned.
2. (b)A person commits a misdemeanor if he or she harms another by any unlawful act in retaliation for anything lawfully done in the capacity of witness or informant.