Mo. Rev. Stat. § 104.422

Upon the death of any member, or former member who has not been refunded his or her accumulated contributions to the fund or received an annuity or benefit, the board shall as soon as practical pay to the beneficiary as the member or former member may have designated in writing, or to his or her estate if no beneficiary be designated, a death benefit equal to the amount of the member's or former member's accumulated contributions.