NEW YORK (AP) - A spray of car-window glass might have made it appear that someone was shooting back when police officers fired a 50-bullet barrage that killed an unarmed driver, a private crime-scene analyst testified.

In simulations, shards of a passenger window flew both into and away from a car when a bullet pierced the glass, expert Alexander Jason testified Monday at the trial of three detectives charged in the fatal shooting of Sean Bell.

His testimony could bolster the detectives' argument that they believed they were in danger when they opened fire and kept shooting at Bell's car, killing him and seriously wounding two of his friends on Nov. 25, 2006 - Bell's wedding day. The shooting happened outside a Queens topless bar where undercover detectives were investigating allegations of prostitution.

Detectives Gescard Isnora and Michael Oliver have pleaded not guilty to manslaughter, and Marc Cooper has pleaded not guilty to reckless endangerment.

They maintain that the shooting was justified in part because they overheard one of Bell's friends threaten to get a gun after Bell had a run-in with another man outside the club.