But it's not clear what led to the incident in which 48-year-old Defarra Ivan Gaymon of Suwanee was shot once in the chest.
County Prosecutor Robert Laurino said Saturday that the detective, whose name has not been released, was investigating complaints of sexual activity occurring in public when he encountered Gaymon around 6 p.m. Friday.
Laurino said it's not known why Gaymon — a former Montclair resident who was in New Jersey for a social event — was in the park or what transpired before the shooting occurred. The detective was taken to University Hospital in Newark shortly after the shooting and was medicated, so investigators have not been able to interview him.
Gaymon's pickup truck was found parked near the scene of the shooting and has been impounded, but he was not in the vehicle when the shooting occurred. He also was taken to University Hospital, where he was pronounced dead shortly after 9 p.m.
The prosecutor's office and the sheriff's office will investigate the incident, which was the third law-enforcement related shooting in Newark this week and the fifth in the past month.
A county grand jury also will review the shooting, which is standard policy for police shootings.