Mo. Rev. Stat. § 105.050
If any vacancy shall happen from any cause in the office of the attorney general, circuit attorney, prosecuting attorney or assistant prosecuting attorney, the governor, upon being satisfied that such vacancy exists, shall appoint some competent person to fill the same until the next regular election for attorney general, prosecuting attorney or assistant prosecuting attorney, as the case may be; provided, in the case of a vacancy in the office of prosecuting attorney, if there is no qualified person in the county who can or will accept such appointment, then the governor may appoint any person who possesses all the qualifications set forth in section 56.010, except the qualification as to residence.
§ 105.050, RSMo
RSMo 1939 § 12989, A.L. 1947 V. I p. 217