Mo. Rev. Stat. § 324.1116: Agency hiring criteria.

A private investigator agency or private fire investigator agency shall not hire any individual as an employee unless the individual:

(1) Is at least twenty-one years of age;

(2) Provides two recent photographs of themselves, of a type prescribed by the board;

(3) Has been fingerprinted in a manner approved by the Missouri state highway patrol, central repository, under section 43.543; and

(4) Complies with any other qualifications and requirements the board adopts by rule.