N.J. Stat. § 30:9-23.5
Any person heretofore or hereafter appointed pursuant to the act of which this act is a supplement whose compensation is paid partly by the county and partly by the municipality, shall, by reason of such appointment, immediately become entitled to participate in all benefits of the respective retirement systems and pension funds of such county and municipality based upon the financial contributions by such person made to such retirement systems or funds.
If such person, at the time of such appointment, is already a member of either a county or municipal retirement system or fund, and as such is entitled to benefits under such retirement system or fund, and shall desire to transfer any portion of such benefits either from a county retirement system or fund to a municipal retirement system or fund, or from a municipal retirement system or fund to a county retirement system or fund, such person under the direction of the administrative heads of such two systems or funds may cause any financial credits to which he may be entitled in either one of said retirement systems or funds, to be transferred to the other retirement system or fund and thereafter shall enjoy the benefits arising out of such credits thus transferred, in the retirement system or fund to which they have thus been transferred, in the same manner as if they had originally accrued therein; credits thus transferred to be deducted in the system or fund in which they originated and the benefits of such person in such original system or fund to be reduced accordingly.
N.J.S. § 30:9-23.5