Mo. Rev. Stat. § 21.410: Writs and process may be issued.

Each house, or both houses in joint meeting, may cause to be issued necessary writs and process to summon and compel any person charged with any offense, whereof they have jurisdiction, to appear before them or any committee, and carry into execution their orders and sentences, and to summon and compel the attendance of witnesses in as full a manner as any court of law, and with like effect.