Philip Nguyen says his family lights a candle every day in memory of Constable Bill Crews, because he feels "sad and regretful" about the police officer's death in a shoot-out during a drug raid.

Nguyen has pleaded guilty to the manslaughter of Constable Crews, 26, who died from a bullet to the head during what he and his fellow officers thought was a low-risk drug raid on a basement car park in Bankstown on the night of September 8, 2010.

Regret ... Philip Nguyen. Credit:James Brickwood

As they entered the car park Nguyen, 57, jumped out from behind a car brandishing a silver pistol and fired a number of shots.

The trainee detective was struck in the arm by a shot from Nguyen, but was killed by a stray bullet from one of his fellow officers, which struck him in the back of the head.