Mo. Rev. Stat. § 43.160
It shall be the duty of the patrol to police the highways constructed and maintained by the commission; to regulate the movement of traffic thereon; to enforce thereon the laws of this state relating to the operation and use of vehicles on the highways; to enforce and prevent thereon the violation of the laws relating to the size, weight and speed of commercial motor vehicles and all laws designed to protect and safeguard the highways constructed and maintained by the commission. It shall be the duty of the patrol whenever possible to determine persons causing or responsible for the breaking, damaging or destruction of any improved hard surfaced roadway, structure, sign markers, guard rail, or any other appurtenance constructed or maintained by the commission and to arrest persons criminally responsible therefor and to bring them before the proper officials for prosecution. It shall be the duty of the patrol to cooperate with such state official as may be designated by law in the collection of all state revenue derived from highway users as an incident to their use or right to use the highways of the state, including all license fees and taxes upon motor vehicles, trailers, and motor vehicle fuels, and upon, with respect to, or on the privilege of the manufacture, receipt, storage, distribution, sale or use thereof (except the sales tax on motor vehicles and trailers, and all property taxes).
§ 43.160, RSMo