Mo. Rev. Stat. § 575.270: Tampering with a witness or victim — penalties.

1. A person commits the offense of tampering with a witness or victim if:

(1) With the purpose to induce a witness or a prospective witness to disobey a subpoena or other legal process, absent himself or herself, avoid subpoena or other legal process, withhold evidence, information, or documents, or testify falsely, he or she:

(a) Threatens or causes harm to any person or property; or

(b) Uses force, threats or deception; or

(c) Offers, confers or agrees to confer any benefit, direct or indirect, upon such witness; or

(d) Conveys any of the foregoing to another in furtherance of a conspiracy; or

(2) He or she purposely prevents or dissuades or attempts to prevent or dissuade any person who has been a victim of any crime or a person who is acting on behalf of any such victim from:

(a) Making any report of such victimization to any peace officer, state, local or federal law enforcement officer, prosecuting agency, or judge;

(b) Causing a complaint, indictment or information to be sought and prosecuted or assisting in the prosecution thereof;

(c) Arresting or causing or seeking the arrest of any person in connection with such victimization.

2. The offense of tampering with a witness or victim is a class A misdemeanor, unless the original charge is a felony, in which case tampering with a witness or victim is a class D felony. Persons convicted under this section shall not be eligible for parole.