Mo. Rev. Stat. § 324.1104: Prohibited acts.

Unless expressly exempted from the provisions of sections 324.1100 to 324.1148:

(1) It shall be unlawful for any person to engage in the private investigator business or carry out a private fire investigation in this state unless such person is licensed as a private investigator or private fire investigator under sections 324.1100 to 324.1148;

(2) It shall be unlawful for any person to engage in business in this state as a private investigator agency or private fire investigator agency unless such person is licensed under sections 324.1100 to 324.1148.