California Code, Business and Professions Code - BPC § 7541

(a) Except as otherwise provided by this section, an applicant, or his or her manager, for a license as a private investigator shall have had at least three years' experience in investigation work.One year's experience shall consist of not less than 2,000 hours of actual compensated work performed by each applicant preceding the filing of an application.

(b) An applicant shall substantiate the claimed years of qualifying experience and the exact details as to the character and nature thereof by written certifications from the employer or qualified manager, subject to independent verification by the director as he or she may determine.

(c) An employer who is a licensee or qualified manager shall respond in writing within 30 days to an applicant's written request for certifications of the applicant's work experience as an employee and either provide the certifications or the reasons for denial. If the applicant notifies the director in writing, under penalty of perjury, that the applicant is unable to obtain the required written response from a licensee or qualified manager, or provides the licensee's or qualified manager's written denial and states, under penalty of perjury, that the licensee's or qualified manager's reasons for denial are invalid or insufficient and the director concurs, the director may require the licensee or qualified manager to provide the bureau with all relevant employment records maintained pursuant to Section 7531.5 regarding the applicant for evaluation in substantiating the applicant's employment experience.