Mo. Rev. Stat. § 56.291

The prosecuting attorney in counties of the third and fourth class, in addition to his other duties provided by law, shall submit to the attorney general of the state of Missouri, a written brief summarizing the facts and law of the lower court proceedings had in all criminal cases appealed to the supreme court from the county of his jurisdiction. The provisions of this section shall not apply to counties of the fourth class having an assessed valuation of less than ten million dollars, unless approved by the county commission.