Mo. Rev. Stat. § 86.288
In addition to any other benefits payable, notwithstanding any provisions of sections 86.280 and 86.287 to the contrary, if a member dies while commissioned as a peace officer, or after retiring and before receiving a refund of the member's mandatory contributions in accordance with section 86.253 or 86.290, or while receiving a disability retirement allowance in accordance with section 86.253 or 86.257, the total amount of the member's mandatory contributions to the retirement system shall be paid without interest to the surviving spouse of such member. Payment pursuant to this section shall be made within sixty days after the later of the date proper proofs of death are provided or August 28, 1994, regardless of when the member died or actually retired, provided that the surviving spouse shall be alive on the date that payment is made.
§ 86.288, RSMo