Witness tampering / 18 U.S.C. Sec. 1512(b)(1) is the act of attempting to alter, destroy, influence, or prevent the truthful testimony of any witness in a federal criminal proceeding. There are three main types of witness tampering prohibited under 18 U.S.C. Sec. 1512(b)(1): 1. Tampering with a witness, victim, or informant: This means attempting to corruptly persuade or induce a witness, victim, or informant to either testify falsely or to withhold their testimony. 2. Retaliating against a witness, victim, or informant: This means attempting to retaliate against a witness, victim, or informant for providing information regarding a federal crime or for testifying truthfully in a federal criminal proceeding. 3. Obstructing a criminal investigation: This means attempting to prevent, hinder, or delay the communication of information regarding a federal crime to a federal law enforcement officer or judge. All of these types of witness tampering are felonies punishable by up to 20 years in prison.