N.J. Stat. Ann. § 43:10-58

The board of chosen freeholders of said county shall have the management and control of such fund and is hereby empowered to make all necessary rules and regulations concerning the same not inconsistent with this article. All moneys not needed for the immediate payment of such pension shall be invested by such board of chosen freeholders, in interest-bearing bonds of any municipality in this state or in any other interest-bearing securities in which savings banks of this state are authorized to invest their funds.