It is prudent to always make sure that you first verify that any person, business or entity advertising or otherwise offering services as a Private Investigator within the State of California is licensed prior to retaining that person, business or entity. Private Investigator Licensing is managed by the Bureau of Security and Investigative Services through the California Department of Consumer affairs.  You can visit their website by clicking the link above or by visiting http://www.bsis.ca.gov/