Mo. Rev. Stat. § 106.250

When an affidavit has been filed with the clerk of the circuit court of any county in this state, as provided in sections 106.230 and 106.240, the governor may, in his discretion, direct the attorney general to assist in the prosecution against said officer; and in case of the refusal of the prosecuting attorney or special prosecutor, after the filing of the affidavit provided for in sections 106.230 and 106.240, to file a complaint, the attorney general shall have authority to file a complaint against the official complained of.