N.J. Stat. § 43:10-20
In first, second, third and fifth class counties of this State, now or hereafter having county detectives, any county detective who shall have served as such for a continuous period of 20 years, and shall have reached the age of 60 years, shall, upon application in writing to the prosecutor of the pleas of his county, be retired upon 1/2 pay.
When a county detective of any of the aforesaid counties has served as such for a continuous period of 20 years and has reached the age of 72 years he shall be retired from such service of the county in which he is employed and he shall receive, for the period of his life, a pension equal to 1/2 of his annual salary at the time of his retirement.
When a county detective of any of the aforesaid counties has served in the aggregate 30 years as a county detective and as a policeman of a municipality, a county, or the State, or either or any of said political subdivisions or the State, and has reached the age of 55 years, he shall be entitled to retire from such service of the county in which he is employed and he shall receive for the period of his life a pension equal to 1/2 of his annual salary at the time of his retirement, provided, immediately before his retirement he is a contributing member to a county pension fund.
N.J.S. § 43:10-20