Mo. Rev. Stat. § 388.610
The director of the department of public safety shall approve applications and appoint such railroad policemen as he deems proper, taking into consideration, among other things, the education, training and experience of each person so appointed concerning the powers of peace officers and the limitations on powers of peace officers in regard to the constitutional rights of citizens to be secure in their persons and property. Those approved, appointed, and commissioned by the director of the department of public safety shall be issued commissions by the director of the department of public safety, and each of them, before entering into the performance of his duties, shall subscribe before the clerk of a circuit court of this state, an oath in the form prescribed by Section 11, Article VII, of the Constitution of this State, to support the constitution and laws of the United States and the state of Missouri, to faithfully demean himself in the office and to faithfully perform the duties of the office, and each of them shall enter into a surety bond in the sum of ten thousand dollars payable to the state of Missouri, conditioned upon the faithful performance of his duties. The executed oath of office, together with a copy of the commission and the bond, shall be filed with the director of the department of public safety until the commission is terminated or revoked as provided in this section. As used in this section relating to railroad policemen, the word "commission" means a grant of authority to act as a peace officer.
§ 388.610, RSMo