Mo. Rev. Stat. § 559.201: Board of probation and parole created, 6th, 7th and 16th circuits — powers.

1. In each judicial circuit in this state composed of a single county wherein there is located a city having not less than four hundred thousand inhabitants and not more than seven hundred thousand inhabitants, a board of probation and parole is created to be composed of the several circuit judges of the judicial circuit.

2. The circuit judges of the circuit shall by majority vote select one of their number as chairman of the board of probation and parole. The chairman and any two or more of the circuit judges may grant, revoke, alter or terminate probation and paroles as provided for by law in sections 559.012 to 559.036.