From Consumer Wiki
A private investigator is an individual who (1) investigates crimes, (2) investigates the identity, business, occupation, character, etc., of a person, (3) investigates the location of lost or stolen property, (4) investigates the cause of fires, losses, accidents, damage or injury, or (5) secures evidence for use in court. Private investigators may protect persons only if such services are incidental to an investigation; they may not protect property. An individual, partnership, or corporation licensed as a private investigator may employ a qualified manager to manage the business on a day-to-day basis.
A license with the Bureau of Security and Investigative Services is required to work as a Private Investigator.
Bureau of Security and Investigative Services
P.O. Box 989002
West Sacramento, CA 95798-9002