Cal. Gov't Code § 75111

(a) Whenever a person entitled to payment of a member’s contributions or any other benefit fails to claim the payment or cannot be located or a warrant in payment is canceled pursuant to Section 17070, the amount owed from the retirement fund shall be administered in accordance with subdivision (c).
(b) Whenever the amount of a benefit payable by this system cannot be determined because the recipient cannot be identified or information necessary to determination of the benefit to be paid cannot be acertained, the contributions of the member on whose account the benefit is payable shall be administered in accordance with subdivision (c).
(c) Notwithstanding any provision of law to the contrary, the amounts described in subdivisions (a) and (b) shall be held, or if a warrant has been drawn the warrant shall be redeposited in the retirement fund and held for the claimant without accumulation of interest, and the redeposit shall not operate to reinstate the membership of the person with respect to whose membership the refund or benefit was payable in this system. If the proceeds, whether heretofore or hereafter redeposited, are not claimed within four years after the date of the redeposit, they shall revert to and become a part of the fund. Transfer to the fund shall be made as of the June 30th next following the expiration of the four-year period.
The board may at any time after transfer of proceeds to the fund upon receipt of proper information satisfactory to it, return the proceeds to the credit of the claimant, to be administered in the manner provided under this system.