Discharge of any officer with probationary status and discharge, demotion, or suspension of any officer with nonprobationary status shall be only for cause, which shall be clearly stated in a written complaint, sworn to by the person preferring the charges, and served upon the officer complained of.

Upon being so served, any such officer shall be entitled to a public hearing before a trial board consisting of two Washington state patrol officers of the rank of captain, and one officer of equal rank with the officer complained of, who shall be selected by the chief of the Washington state patrol by lot from the roster of the patrol. In the case of complaint by an officer, such officer shall not be a member of the trial board.