Mo. Rev. Stat. § 87.245

If there are no further benefits otherwise payable under sections 87.120 to 87.370 and the total amount of benefits paid to date is less than an amount equal to the accumulated contributions of the member at his death or at his retirement whichever occurred first, the difference shall be paid to the beneficiary named to receive the amount or if no such beneficiary is living, to the beneficiary or the estate of the beneficiary last entitled to benefits.