N.J. Stat. Ann. § 43:10-35

The board of chosen freeholders of the county shall have the management and control of the fund and may make all necessary rules and regulations concerning the same not inconsistent with this article. All moneys not needed for the immediate payment of the pensions shall be invested by the 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 may invest their funds.