Mo. Rev. Stat. § 86.293: Disposition of difference between benefits paid and accumulated contributions.

If there are no further benefits otherwise payable under sections 86.200 to 86.366 and the total amount of benefits paid to date is less than an amount equal to the accumulated contributions of the member at death or retirement, whichever occurred first, the difference shall be paid to the beneficiary named to receive such amount or if no such beneficiary is living, to the beneficiary or the estate of the beneficiary last entitled to benefits.