Accused: Guilty or Innocent? S07E08 - Killer Officer or Drive-by Victim?

Late night in the Bronx, an off-duty Correction Officer believes he's been shot at by the occupants of a vehicle. He returns fire, killing a teenage passenger. A 'Gel Bead Blaster' is found in the vehicle, which the prosecution claims is a toy weapon. Did the accuse use excessive force or was he justified firing his service weapon in self-defense?