Mo. Rev. Stat. § 544.420: Recognizance, when required.

If it appear that a felony has been committed, and that there is probable cause to believe the prisoner guilty thereof, the associate circuit judge shall bind, by recognizance, the prosecutor, and all material witnesses against such prisoner, to appear and testify before the court having cognizance of the offense, on such day as the prosecuting attorney shall designate in writing duly filed with the associate circuit judge at the time, and not to depart such court without leave.