California Code, Penal Code - PEN § 29880

(a) If the Department of Justice determines that a person prohibited from owning, purchasing, receiving, or possessing a firearm by this chapter, Chapter 3 (commencing with Section 29900), or Section 8100 or 8103 of the Welfare and Institutions Code has attempted to acquire a firearm, or has attempted to report their acquisition or ownership of a firearm in order to have it listed in the registry set forth in Section 11106 as owned by that person, whether the report is mandated by this part or made pursuant to Section 28000, the department shall notify the local law enforcement agency with primary jurisdiction over the area in which the person was last known to reside of the attempt in a manner and format prescribed by the Department of Justice.

(b) If a person described in subdivision (a) is prohibited from owning or possessing a firearm pursuant to Section 8100 or 8103 of the Welfare and Institutions Code, the department shall also notify the county department of mental health in the county in which the person was last known to reside.