Mo. Rev. Stat. § 292.230

In case of an offense which is a violation of sections 292.010 to 292.250 and of some other law of this state, then the director or assistant director may elect under which law he will prosecute; but where an offense is in violation of some other law of this state in relation to the protection of employees, but is not covered by sections 292.010 to 292.250, then it shall be the duty of the director or assistant director to prosecute for all such offenses under the law violated.