RCW 9A.72.120: Tampering with a witness.

(1) A person is guilty of tampering with a witness if he or she attempts to induce a witness or person he or she has reason to believe is about to be called as a witness in any official proceeding or a person whom he or she has reason to believe may have information relevant to a criminal investigation or the abuse or neglect of a minor child to:

(a) Testify falsely or, without right or privilege to do so, to withhold any testimony; or

(b) Absent himself or herself from such proceedings; or

(c) Withhold from a law enforcement agency information which he or she has relevant to a criminal investigation or the abuse or neglect of a minor child to the agency.

(2) Tampering with a witness is a class C felony.

(3) For purposes of this section, each instance of an attempt to tamper with a witness constitutes a separate offense.