Mo. Rev. Stat. § 454.420
Any legal action necessary to establish or enforce support obligations owed to the state shall be brought by prosecuting attorneys, or other attorneys under cooperative agreement with the family support division, upon being furnished notice by the division of such obligation. If the amount of the support obligation owed to the state has not been determined because no court order exists, the family support division may refer the case to the appropriate prosecuting attorney, or other attorney under cooperative agreement with the division, for establishment and enforcement of a support order or order for reimbursement. When a recipient is no longer eligible for aid to families with dependent children benefits, the assignment shall terminate, unless the recipient and the family support division agree otherwise, except for those unpaid support obligations still owing to the state under the assignment at the time of the discontinuance of aid. Upon referral from the family support division, such unpaid obligations shall be collected by the prosecuting attorney, or other attorney under cooperative agreement with the division, up to the amount of unreimbursed aid paid by the family support division prior to or after execution of the assignment of support rights. Moneys collected pursuant to this section shall be paid to the department of social services for deposit in the child support enforcement fund in the state treasury.
§ 454.420, RSMo