The sources told ABC News it was not clear how close the two sides came to an agreement before the negotiations stopped.
Federal prosecutors in New York signaled in a letter to the court Friday that they would not appeal a judge's decision that removed the death penalty from consideration in the case against Luigi Mangione.
Luigi Mangione's state murder case is tentatively scheduled to begin on June 8, Judge Gregory Carro said on Friday.
Luigi Mangione has been called to court on February 6. The summons notification did not include a reason for the unexpected court appearance.
A federal judge in New York has dismissed the death-eligible counts from Luigi Mangione's indictment. The same judge declined to suppress evidence seized from his backpack.
Luigi Mangione should stand trial in state court in July, at least three months ahead of when the accused killer could stand trial in federal court, the DA's office said.
