N.J. Stat. § 2A:160-4
Immediately after the person to whom the money has been advanced by the county treasurer, as provided by N.J.S. 2A:160-3, shall have completed the duties for which such money was advanced, he shall file with the county treasurer an itemized statement or account of the necessary expenses incurred in the performance of such duties, duly verified, certified to and approved under the hand of the prosecutor, and with the written approval of the Assignment Judge in such county. If the itemized statement or account so rendered and approved, as aforesaid, should exceed the sum of money so advanced to such person, the balance thereof shall be paid to such person by the county treasurer; and if the sum of money advanced to such person shall exceed the amount of his itemized statement or account of expenses, as the same shall be so certified and approved, such person shall forthwith return the excess money to the county treasurer.
N.J.S. § 2A:160-4