Braszczok did nothing to stop the assault, prosecutors said. He didn't call 911 and didn't report it to his superiors for two days, and then when he did he lied about it, Assistant District Attorney Samantha Turino said. At first Braszczok told investigators he didn't see the attack, then changed his story to say he saw it but didn't participate, she said.
The detective was stripped of his gun and badge after internal affairs detectives discovered he was present for at least part of the encounter. He initially told authorities and his union that he left without intervening in part because of his role as an undercover officer.
Uniformed officers, even off duty, are expected to jump in if a crime is occurring, but rules are murkier for undercover officers, who face blowing their covers if they come forward.
Investigators discovered video evidence showing Braszczok punching an already damaged back window, causing it to shatter, then twice kicking the passenger side of the SUV before leaving the scene, prosecutors said.
Several bikers also have been charged with attacking Lien or his SUV or instigating the melee.
Clint Caldwell was charged Wednesday with gang assault after prosecutors said he pulled the shattered glass from Lien's window and reached inside the SUV. His lawyer said there's no video showing him with his hands inside the SUV.
Police charged another biker, James Kuehne, with gang assault, weapon possession and other crimes. It was unclear if Kuehne had an attorney, and a message left at his Brooklyn home wasn't immediately returned.
Lien's wife has said he fled to protect her and their 2-year-old daughter. Lien hasn't been charged with any crime.