Mo. Rev. Stat. § 409.536
The attorney general may prosecute every person charged with the commission of a criminal offense arising from the violation of any provision of sections 409.500 to 409.566. In all such proceedings, the attorney general may appear in person or by his deputy before any court of record or any grand jury and exercise all the powers and perform all the duties in respect of such actions or proceedings which the prosecuting attorney would otherwise be authorized or required to exercise or perform; or the attorney general may in his discretion transmit evidence, proof and information as to such offense to the prosecuting attorney of the county or counties in which the alleged violation has occurred, and every prosecuting attorney to whom such evidence, proof and information is so transmitted shall forthwith proceed to prosecute any corporation, company, association, or officer, manager or agent thereof, or any firm or person charged with such violation. In any such proceeding, wherein the attorney general has appeared either in person or by deputy, the prosecuting attorney shall only exercise such powers and perform such duties as are required of him by the attorney general or the deputy attorney general so appearing.
§ 409.536, RSMo