N.J. Stat. § 43:11-4
Any person who, while holding any office, position or employment in any municipality of this State and while a member of and entitled to benefits in any retirement system or pension fund operated wholly in such municipality and to which system or fund the member contributes, accepts or is transferred to an office, position or employment in another branch of service of said municipality, shall remain a member of such retirement system or pension fund notwithstanding such transfer, whether voluntary or involuntary, from the branch of service in which said pension fund or retirement system is maintained and shall continue to be entitled to all the benefits of said pension fund or retirement system under the same conditions, and deductions and contributions to said pension fund or retirement system shall be made for him, as though he had not so transferred from said branch of service.
N.J.S. § 43:11-4