Authorities have revealed how an imprisoned ex-cop once accused of injuring Jeffrey Epstein‘s neck previously killed a man — with a zip tie around his throat, according to new court papers.

Former Briarcliff Manor Officer Nicholas Tartaglione — who was suspected of hurting Epstein while the pair were cellmates in a Manhattan jail in July — was arrested in December 2016 for murdering four men, including one named Martin Luna, who the ex-cop accused of swiping drug money from him, officials have said.

But authorities couldn’t determine exactly how Luna was killed.

According to the feds, Tartaglione had lured Luna and two of his relatives and a friend to a local lounge, where the former cop and some accomplices pounced.

The new Manhattan federal-court filing now says Tartaglione “then hit Luna repeatedly and eventually put a plastic zip tie around Luna’s neck and pulled it tight, choking Luna, and ultimately killing him.”

The other three men with Luna were shot in the head, authorities have said.

Tartaglione is cooling his heels in the Metropolitan Correctional Center in Lower Manhattan awaiting trial.

Epstein, a convicted pedophile who had been facing sex-trafficking charges, was briefly paired with him in a cell and told his lawyers that July 23, the ex-cop inflicted injuries on him that nearly left him unconscious, a source told The Post at the time. Epstein was treated for neck injuries, law-enforcement officials said.

Tartaglione’s lawyer denied the claim that his client hurt Epstein.

Epstein was moved out of the cell and hanged himself within weeks.