California Code, Probate Code - PROB § 12403

(a) If the missing person was a resident of this state when last seen or heard from, the superior court of the county of the person's last known place of residence has jurisdiction for the purposes of this part.

(b) If the missing person was a nonresident of this state when last seen or heard from, the superior court of a county where real property of the missing person is located, or of a county where personal property is located if the missing person has no real property in this state, has jurisdiction for the purposes of this part.