N.J. Stat. § 43:16A-42
Any police employee of any such county park commission may become a member by filing with the board of trustees his election in writing to become such member at any time within 6 months after this act becomes effective. Each such police employee so electing to become a member shall file with the board of trustees a detailed statement of all service rendered by him as a police employee of such county park commission prior to the date of his application and for which he claims credit. As soon as practicable thereafter the board of trustees shall verify such statement and shall issue to him a prior service certificate certifying to the aggregate length of such service allowable as creditable service. Such certificate shall be final and conclusive for retirement purposes as to such service, unless thereafter modified by the board of trustees upon application made by the member within 1 year, or upon its own initiative within 1 year after the date of issuance of such prior service certificate.
N.J.S. § 43:16A-42