A fund shall be created in the following manner for the purpose of paying such pensions, to wit: There shall be deducted from every payment of salary to each county detective three per cent of the amount thereof; then there shall be contributed annually by the county an amount equivalent to three per cent of said detectives' salaries; to said fund there shall be added all moneys donated for the purpose of such fund, and all rewards which may be paid to any county detective while acting as such county detective, all of which moneys and rewards shall be paid over to the board of chosen freeholders of the county to be deposited in such fund. In case, at any time, there shall not be sufficient money in such pension fund to pay such pensions, the board of chosen freeholders of the county shall, from time to time, include in any tax levy a sum sufficient to meet the requirements of such pension fund. Whenever such pension fund shall exceed an amount which the board of chosen freeholders of such county shall by resolution from time to time determine to be adequate for such pension fund, no moneys, except the three per cent specified in this section, and the moneys given or donated as herein mentioned and any aforementioned rewards, shall be paid into such fund unless and until the amount of such fund shall fall below the amount thus determined to be adequate.
N.J.S. § 43:10-28