Mo. Rev. Stat. § 566.224
No prosecuting or circuit attorney, peace officer, governmental official, or employee of a law enforcement agency shall request or require a victim of sexual assault under section 566.040 or forcible rape under section 566.030 to submit to any polygraph test or psychological stress evaluator exam as a condition for proceeding with a criminal investigation of such crime.
(L. 2007 H.B. 583)