Mo. Rev. Stat. § 58.765

Any two or more counties adopting the provisions of sections 58.010, 58.020, 58.060, 58.090, 58.160, 58.375, 58.451, 58.455 and 58.700 to 58.765 or to whom sections 58.010, 58.020, 58.060, 58.090, 58.160, 58.375, 58.451, 58.455 and 58.700 to 58.765 apply may by contract among themselves join in the appointment of a county medical examiner to serve all such counties. The governing body of all the counties shall approve the contract, administer the appointment and allocate the costs among the counties.