N.J. Stat. Ann. § 40A:9-117.16

A candidate for the position of sheriff's officer chief shall be a citizen of the United States, and a resident of the county of appointment for at least three years next preceding his appointment. In addition, a candidate shall be certified by the Police Training Commission as having completed a police training course at an approved school, pursuant to P.L.1961, c.56 (C.52:17B-66 et seq.), and shall have at least 10 years' experience in law enforcement.