Mo. Rev. Stat. § 166.121: State, the trustee.

The state of Missouri is hereby constituted the custodian and trustee under sections 166.061 to 166.121 of all such funds, and pledges itself for the safekeeping, investment and due application of all funds, with the interest thereon, which may be received by the director of revenue or deposited in the treasury in pursuance of sections 166.061 to 166.121.