The state attorney general’s office on Tuesday took over the investigation into the shooting of a Brooklyn man by an off-duty cop stemming from an episode of road rage over the weekend.

The cop, identified by a source as Wayne Isaacs, had finished his shift at the 79th Precinct when he and 37-year-old Delrawn Small both stopped at a red light in Cypress Hills just after midnight on Monday, police said. Small apparently got out of his car and, without exchanging any words, started to punch Isaacs.

That’s when Isaacs pulled out his service weapon and fired, fatally striking Small in the head, cops said. Isaacs, who has been an officer for three years, was treated at Jamaica Hospital Medical Center for contusions to his head.

“The Attorney General has determined that this case falls within the parameters of the Executive Order and has launched a full investigation,” a spokesman for Attorney General Eric Schneiderman said in a statement.

This is the sixth such case the AG’s office has taken over, and the second such case in the city. Schneiderman also took over the investigation into the death of Richard Gonzalez, who died in March after being handcuffed after police responded to a call that Gonzalez had taken drugs and become aggressive.

A representative for the NYPD did not immediately respond to a request for comment.

Gov. Andrew Cuomo signed an executive order in July 2015, giving the attorney general the ability to take over cases in which a law enforcement officer killed an unarmed civilian. The order came after several high-profile police killings and was supported by the families of those victims, including Eric Garner and Ramarley Graham.

Correction: A previous version of this article incorrectly attributed a quote to Attorney General Eric Schneiderman.