N.J. Stat. § 43:10-18.26
The board of chosen freeholders in any county of this State having a population of more than eight hundred thousand inhabitants may retire any court attendant in the office of the sheriff, and any guard, keeper, nurse and other employee engaged in the safe-keeping and care of prisoners in the county jail and the county penitentiary, who shall have served as such for a period of twenty years, and shall have reached the age of sixty-five years, and who, at that time, is a member of the employees' retirement system of such county provided for by the act of which this act is supplementary under the provisions of said act; provided, however, subject to the approval of the board of chosen freeholders, that any such person may be continued in his or her county employment after reaching the age of sixty-five, if the sheriff or warden of the jail or penitentiary, as the case may be, shall file a certificate with the board of chosen freeholders and the pension commission of the county, certifying that such person is in good physical and mental condition and able to fully perform his or her duties, in which event such employee shall be permitted to remain in employment for a period not exceeding one year from the date of the certificate. Such certificates may, in the discretion of the sheriff or warden, as the case may be, be renewed annually until after such person shall have reached the age of seventy.
N.J.S. § 43:10-18.26