Mo. Rev. Stat. § 57.355: Additional duty, investigation of jurors (second class counties).

Sheriffs in counties of the second class shall, in addition to other duties imposed upon them by law, aid and assist the jury commissioners in such counties by conducting investigations into the identity of prospective jurors summoned for jury duty, and upon request of the board of jury commissioners, make and file a report with the board setting out the results of the investigation.