Officer Michael Morgan, 32, was off duty when he was shot to death outside a strip club in Paterson in 2011.
He was attending a friend's birthday celebration, reportedly walking a dancer to her car.
A judge is expected to accept a plea agreement for alleged shooter Jerome Wright.
Wright's girlfriend, Nashali Gadson, is expected to plead guilty to a robbery charge connected to the shooting.
The pair allegedly tried to rob the dancer, when Morgan intervened.