As used in this chapter:
(a) “Authorized agency” means any of the following officers or agencies, or their duly authorized representatives, when investigating or prosecuting arson in connection with a specific fire: the State Fire Marshal, the Director of the Department of Forestry and Fire Protection, the chief of any city or county fire department, the chief of any fire protection district, the Attorney General, any district attorney, or any peace officer, the Department of Insurance, and any federal agency.
(b) “Insurer” means any insurer admitted to write, or otherwise issuing, fire insurance covering property in this state and includes its agents, servants, investigators, and adjusters. “Insurer” includes the California FAIR Plan.