C.R.S. § 18-8-707

(1) A person commits tampering with a witness or victim if he intentionally attempts without bribery or threats to induce a witness or victim or a person he believes is to be called to testify as a witness or victim in any official proceeding or who may be called to testify as a witness to or victim of any crime to: (a) Testify falsely or unlawfully withhold any testimony; or (b) Absent himself from any official proceeding to which he has been legally summoned; or (c) Avoid legal process summoning him to testify. (2) Tampering with a witness or victim is a class 4 felony.