In counties of the first class there may be appointed not in excess of 30 county investigators, who shall be paid annual salaries of not less than $6,500.00.

L.1951 (1st SS), c.344; amended by L.1959, c. 161, s.7, p. 637, L.1966, c. 265, s. 1, eff. Sept. 6, 1966.