An NYPD cop was charged with second-degree murder Monday in an off-duty road-rage shooting in Brooklyn that left another driver dead in the street — marking the first case brought under an executive order signed in the wake of the Eric Garner killing, sources said.

Wayne Isaacs, 37, was indicted on the rap, along with first-degree manslaughter, by a Brooklyn grand jury following a probe by state Attorney General Eric Schneiderman, who last year began serving as a special prosecutor for all police killings of civilians in New York, sources said.

Isaacs is the first cop charged by the special prosecutor since Gov. Andrew Cuomo appointed Schneiderman to that role in August 2015, nearly a year to the day after Garner’s chokehold death during his arrest on Staten Island.

At the time, Cuomo said he was addressing a “crisis of confidence in the criminal justice system” in a bid to prevent “anarchy.”

Isaacs is accused of gunning down Delrawn Small, also 37, during a confrontation on Atlantic Avenue in East New York that unfolded early July 4 in front of the victim’s girlfriend and two kids.

Surveillance video exclusively obtained by The Post shows Isaacs, who was in civilian clothing and driving home after finishing a shift at the 79th Precinct, waiting just 1 second before opening fire after Small charges over to his car.

Small, an ex-con with a lengthy rap sheet, drove after Isaacs in a rage for about seven blocks because he believed the cop had cut him off, police sources have said.

His girlfriend also told cops that Small had downed three drinks at a barbecue before the incident, and ignored her plea not to get out of his car.

Small’s niece publicly threatened that she and her friends would be “hunting…down” Isaacs to “seek our justice” if he wasn’t charged.

The deadly incident also sparked a protest by members of the Black Youth Project 100 outside the headquarters of the Police Benevolent Association, where at least 10 people were arrested on July 20.

Small was black, as is Isaacs.