Police say they received information last Friday night that Victor Caba was carrying a variety of police gear and driving a blue Volvo around the city.
Detectives spotted the vehicle at Paulison Avenue and Oak Street.
When they went to question Caba, he identified himself as a Essex County Sheriff Special investigator, authorities say.
He was charged with impersonating a police officer and unlawful possession of a weapon.
He also had a traffic warrant out of Paterson and was driving with a suspended driver's license, according to police. His bail was set at $75,000 and he was bailed out on Sunday.