GOV § 24105

If the office of any of the county officers enumerated in Section 24000 of this code is vacant the duties of such office may be temporarily discharged by a chief deputy, assistant or deputy of such officer, as the case may be, next in authority to such county officer in office at the time the vacancy occurs, with like authority and subject to the same obligations and penalties as such county officer, until the vacancy in the office is filled in the manner provided by law; provided that if the vacancy occurs in the office of sheriff, the duties of such office shall be discharged by the undersheriff, or if that position is vacant, by the assistant sheriff, or if that position is also vacant, by the chief deputy next in line of authority.