Mo. Rev. Stat. § 56.190
In all counties of class one, the stenographers in the office of the prosecuting attorney shall, when so directed by the prosecuting attorney of such county, take down and transcribe for the use of the prosecuting attorney testimony and evidence before the grand jury of said county and before any court of said county exercising criminal jurisdiction or before the coroner of said county at any inquest held on any homicide or felony inquiry, and shall perform such other duties in the office of the prosecuting attorney as may be necessary. Before taking down any evidence before the grand jury such stenographers shall be sworn to keep secret any fact disclosed in said grand jury room, and shall not divulge any testimony which he or she may have heard there, except to the prosecuting attorney or when lawfully required to do so by a court of record having jurisdiction in said matter.
§ 56.190, RSMo