The indictment Friday says undercover detective Wojciech Braszczok was charged with gang assault, criminal mischief, riot and other counts.
Prosecutors have said Braszczok participated in the Sept. 29 attack by shattering the SUV's back window. He was off duty at the time. Attorney John Arlia didn't immediately return a message seeking comment.
Police say that after the SUV driver bumped a bike that had slowed in front of the vehicle, motorcyclists converged on the vehicle. Police say the driver, while trying to get away, ran over a biker then motorcyclists caught up with the driver and beat him. The driver hasn't been charged.
