The trial against an NYPD officer accused of shooting and killing an unarmed man in a road rage incident while off duty last year began Monday.

Wayne Isaacs faces a charge of second-degree murder in connection to the slaying of Delrawn Small on July 4, 2016.

Isaacs' defense attorney says the off-duty officer was on his way home from work when Small assaulted him. Prosecutors say it wasn't self-defense.

If convicted, Isaacs could serve 25 years to life in prison.

Small had three children, according to his sister.