Cal. Gov. Code § 31761

Optional settlement 1 consists of the right to elect in writing to have a retirement allowance paid him or her until his or her death and, if he or she dies before he or she receives in annuity payments the amount of his or her accumulated contributions at retirement, to have the balance at death paid to his or her estate or to the person, having an insurable interest in his or her life, as he or she nominates by written designation duly executed and filed with the board.