In counties of the fifth class with a population of 400,000 or less there may be appointed not in excess of 12 county detectives, and in counties of the fifth class with a population in excess of 400,000 there may be appointed not in excess of 15 county detectives, of whom one may be designated chief of county detectives, two captains of county detectives, and four lieutenants of county detectives.
N.J.S. § 2A:157-8