A mobster who was accused of killing an NYPD detective in 1986 but set free after four trials died at age 84 Friday in New York after an illness, The Post has learned.

Federico Giovanelli was charged with gunning down Detective Anthony Venditti, 34, who was tailing him as part of an investigation into organized-crime activity.

Two state trials ended in hung juries. A federal jury then convicted him of racketeering, but an appeals court overturned the verdict. The Queens jury that finally acquitted him deliberated four days.

“I am disappointed, but I learned a long time ago not to second-guess a jury,” DA Richard Brown said at the time.

No one has ever been convicted in the slaying.

Click for the story in the New York Post.