UnitedHealthcare CEO killing latest: Mangione arrives at court, faces extradition

Luigi Mangione, the suspect in the killing of UnitedHealthcare CEO Brian Thompson, arrived Thursday morning to court in Pennsylvania, where he is expected to waive extradition to New York, according to his attorney.

A Pennsylvania judge must accept the extradition waiver or go forward with a scheduled hearing immediately following a separate hearing on the local charges Mangione faces.

If the extradition paperwork is in order, the New York Police Department would then transport Mangione from Pennsylvania to New York. Mangione could be arraigned in New York as soon as Thursday.

Mangione faces an 11-count indictment by the Manhattan District Attorney's Office and is also expected to face federal charges out of the Southern District of New York, law enforcement sources told ABC News.

SDNY and the FBI's New York field office both declined to comment.

A special edition of "20/20" airing Dec. 19 at 10 p.m. ET on ABC looks at the murder of UnitedHealthcare CEO Brian Thompson and the manhunt that led to the arrest of Luigi Mangione, who went from the Ivy League to alleged killer.

Federal charges could make Mangione eligible for the death penalty. He faces a maximum sentence of life in prison without parole if convicted of the state charges.

Mangione's New York lawyer, Karen Friedman Agnifilo, said in a statement, "The federal government's reported decision to pile on top of an already overcharged first-degree murder and state terror case is highly unusual and raises serious constitutional and statutory double jeopardy concerns."

"We are ready to fight these charges in whatever court they are brought," Agnifilo said.

Danielle Filson, a spokesperson for Manhattan District Attorney Alvin Bragg, said, "The state case will proceed in parallel with any federal case."

Mangione, 26, is accused of gunning down Thompson outside a Hilton hotel on Dec. 4 as the CEO headed to an investors conference. Prosecutors alleged Mangione waited nearly an hour for Thompson to arrive.

A Manhattan grand jury upgraded charges against Mangione to include first-degree murder in furtherance of terrorism, prosecutors announced Tuesday.

The killing in the heart of Midtown Manhattan was "intended to evoke terror," Bragg said.

In New York, Mangione is also charged with two counts of second-degree murder, one of which is charged as killing as an act of terrorism; two counts of criminal possession of a weapon in the second degree; four counts of criminal possession of a weapon in the third degree; one count of criminal possession of a weapon in the fourth degree; and one count of criminal possession of a forged instrument in the second degree.

In Pennsylvania, where Mangione was arrested on Dec. 9 after nearly a week on the run, he faces charges including allegedly possessing an untraceable ghost gun.

Mangione had a 9 mm handgun with a 3D-printed receiver, a homemade silencer, two ammunition magazines and live cartridges when apprehended, prosecutors said.