N.J. Stat. § 43:15A-75.1
Any other law to the contrary notwithstanding, a member of the Public Employees' Retirement System who is in the service of a municipality and who, prior to entering such service was the holder of a position in the service of a county, or who is presently in the service of a county and who, prior to entering such service was the holder of a position in the service of another county, shall be entitled to purchase prior service credit for the years of such county service; but said county shall not be liable for any payment to the system by reason of the said member's purchase of benefits under this supplementary act and contributions required hereunder shall be made by the member. Proof of such prior county service shall be furnished by the affidavit of the member supported by other evidence if required by the board of trustees of said retirement system. The member may purchase credit for such prior county service by making payments to the system either in a lump sum or in regular monthly installments pursuant to such formulas, rules and regulations as may be promulgated by the Division of Pensions.
N.J.S. § 43:15A-75.1