Mo. Rev. Stat. § 442.340: Remedy against persons refusing to appear and answer.

Every person who, being served with such subpoena, shall, without reasonable cause, refuse or neglect to appear or, appearing, shall refuse to answer, upon oath, touching the matters aforesaid, shall forfeit to the party injured one hundred dollars, to be recovered by civil action, and may also be committed to prison by the officer who issued such subpoena, there to remain without bail until he shall submit to answer, upon oath, as aforesaid.