Mo. Rev. Stat. § 103.016

The executive director and all other employees of the plan shall be state employees and eligible for all corresponding benefits. Except by the unanimous vote of the board, no person who has served as a trustee of the board may become an employee of the plan until four years have expired between the date of his or her resignation, termination, or other removal as trustee and the date of his or her appointment as an employee of the plan.