A. A person commits tampering with a witness if the person knowingly communicates, directly or indirectly, with a witness in any official proceeding or a person he believes may be called as a witness to do any of the following:
1. Unlawfully withhold any testimony.
2. Testify falsely.
3. Absent himself from any official proceeding to which he has been legally summoned.
4. Evade a summons or subpoena.
B. Tampering with a witness is a class 6 felony.