Mo. Rev. Stat. § 55.030
The county auditor of a county having a charter form of government shall prescribe, with the approval of the governing body of the county and the state auditor, the accounting system of the county. He shall keep accounts of all appropriations and expenditures made by the governing body of the county; and no warrant shall be drawn or obligation incurred without his certification that an unencumbered balance, sufficient to pay the same, remains in the appropriation account against which such warrant or obligation is to be charged. He shall audit and examine all accounts, demands, and claims of every kind and character presented for payment against such county, and shall approve to the governing body of the county all lawful, true, and just accounts, demands, and claims of every kind and character payable out of the county revenue or out of any county funds before the same shall be allowed and a warrant issued therefor. Whenever the county auditor deems it necessary to the proper examination of any account, demand, or claim, he may examine the parties, witnesses, and others on oath or affirmation touching any matter or circumstance in the examination of such account, demand, or claim. At the direction of the governing body of the county, he shall audit the accounts of all officers and employees of the county and upon their retirement from office and shall keep a correct account between the county and all county officers; and he shall examine all records and settlements made by them for and with the governing body of the county or with each other; and the county auditor shall, at all reasonable times, have access to all books, county records, or papers kept by any county or township officer, employee, or road overseer. He may keep an inventory of all county property under the control and management of the various officers and departments and shall annually take an inventory of any such property at an original value of one thousand dollars or more showing the amount, location and estimated value thereof. He shall perform such other duties in relation to the fiscal administration of the county as the governing body of the county shall from time to time prescribe. The county auditor shall not be personally liable for any costs for any proceeding instituted against him in his official capacity.
§ 55.030, RSMo