N.J. Stat. § 43:10-18.18
From and after July 1, 1943, any employee who is or becomes a member of this retirement system may not withdraw therefrom and shall not be entitled to a refund of any moneys theretofore and thereafter deducted from his salary hereunder; provided, however, that any employee who separates from the county service through his discharge, resignation, or for any other reasons other than retirement shall be entitled to a refund of all moneys theretofore deducted from his salary for the retirement system established hereunder; provided, however, that any member of the retirement system established hereunder who retires on pension under the provisions of any other act, shall be entitled, upon written application made therefore to the pension commission within 3 months after such retirement on pension, to a refund of the moneys theretofore deducted from his salary for the retirement system, and provided, further, that where the service of an employee is terminated by death of the employee, if such employee leaves no widow, dependent widower, or dependent children under 18 years of age, all moneys theretofore deducted from his salary for the retirement system established hereunder shall be paid to the person designated by said employee as his or her beneficiary and if no such designation has been made or if the beneficiary has predeceased said employee, all moneys deducted from his or her salary for the retirement system shall be paid to the estate of the deceased employee.
N.J.S. § 43:10-18.18