Cal. Code Civ. Proc. § 1609
Within 120 days following the date of initial posting by the clerk of the superior court, the Attorney General shall commence a proceeding by filing a petition to determine the state's right to custody of all property mentioned in such report and unclaimed within the time and in the manner provided by Section 1607. The proceeding shall be commenced and heard in the superior court in the County of Sacramento and venue shall not be affected by the provisions of Section 401, Code of Civil Procedure.
The petition shall name as respondents all persons known to have been interested and "all persons unknown claiming any title or interest in or to the property described or referred to in the petition." If the records of the United States fail to disclose with reasonable certainty the identity or number of owners or claimants of specific funds or other personal property, or the extent of their interests therein, such persons may be designated and described as a class, to wit, as "all unknown owners or claimants to the funds or property mentioned in or affected by ____," and, as the case may be, the petition shall identify and set forth the court actions or proceedings to the credit of which such funds or other property are held, or the accounts or other identifying references under which they are carried upon the records of the United States. The petition shall describe or refer to the property, and may include one or more items, as the Attorney General may be advised, without prejudice to his right to commence subsequent proceedings relating to other items not included. The petition shall also state the name of the owner and his last address as known or as presumed under this chapter, and shall set forth the facts and circumstances by virtue of which it is claimed that such funds or property are subject to custody by the state. Any number of respondents may be joined whether they reside in the same or different counties, and any number of causes of action may be joined and need not be separately stated.
Ca. Civ. Proc. Code § 1609