The sources told ABC News it was not clear how close the two sides came to an agreement before the negotiations stopped.
Mark Anderson, 36, allegedly went to the Metropolitan Detention Center in Brooklyn on Jan. 28 posing as a federal agent and claimed to have a court order to release 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.
A Minnesota man allegedly tried to break Luigi Mangione out of jail in New York, law enforcement sources told ABC News.
