An accused drug dealer nabbed after an undercover bust turned fatal in Manhattan last week was acting as “security” for the deal, according to new court papers.

Jefry Silvestre and an unnamed co-conspirator were unknowingly selling cocaine to an informant, the US Drug Enforcement Agency wrote in the Manhattan Federal Court filing.

Silvestre had made the trip from Philadelphia to the Big Apple to bring $15,500 in cash to the co-conspirator, who then mentioned he was about to do a drug deal and asked Silvestre to stay and act as security, prosecutors contend.

But after the informant confirmed the presence of cocaine to cops, things went south at the Vermilyea Ave building in Inwood, where the dealers were working out of a first-floor apartment.

Silvestre was quickly nabbed near the vestibule of the building, allegedly tossing aside a gun as he was taken into custody, but his partner began shooting at cops when they approached, police said in court papers.

Christopher Sadowski

Christopher Sadowski

The officers returned fire, with a bullet from what is believed to be an NYPD gun striking down the trigger-happy dealer, sources previously told The Post.

The operation was carried out by a longstanding federally funded joint task force comprised of 15 agencies, including the NYPD, the DEA, Homeland Security, the IRS’ Criminal Investigation Division, the Bureau of Alcohol, Tobacco, Firearms and Explosives, and others.

Silvestre and the co-conspirator were considered “major players” in the city’s mid-level drug trade, sources said.

Silvestre was held without bail. His lawyer didn’t immediately return a message seeking comment.