Mo. Rev. Stat. § 556.038: Time limitation to prosecute.

Notwithstanding the provisions of section 556.036, either misdemeanor or felony prosecutions under sections 565.252 to 565.257 shall be commenced within the following periods of limitation:

(1) Three years from the date the viewing, photographing or filming occurred; or

(2) If the person who was viewed, photographed or filmed did not realize at the time that he was being viewed, photographed or filmed, within three years of the time the person who was viewed or in the photograph or film first learns that he was viewed, photographed or filmed.