N.J. Stat. Ann. § 43:13-21.1

Whenever a municipal employee of a city of the first class has become a member of the pension fund established for employees of said city, and has, since becoming a member of said pension fund, accepted employment, or has become an officer or employee of the school district of said city, or of the county in which said city is located, and has continued to pay into the pension fund of said city the required contribution under the act which this act supplements, said employee shall be entitled to all the rights and benefits to which an employee under the act which this act supplements is entitled.