UnitedHealthcare CEO killing latest: Luigi Mangione faces federal charges including stalking, murder

Luigi Mangione, the suspect in the killing of UnitedHealthcare CEO Brian Thompson, is charged in a four-count federal criminal complaint with stalking, murder through the use of a firearm and a firearms offense involving a silencer.

He waived extradition on Thursday morning and was transported via plane and helicopter from Pennsylvania to New York.

Mangione is expected to make his initial appearance in federal court in lower Manhattan Thursday afternoon.

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.

Mangione agreed to be extradited during an appearance in court in Blair County, Pennsylvania, on Thursday morning.

Mangione stood as the judge read him his rights. The Ivy League graduate answered "yes" when asked if he understood and answered "yes" when asked if he wanted to waive extradition.

NYPD officers sat in the front of the courtroom and took custody of Mangione after his appearance.

Spectators gathered outside the courthouse as Mangione was taken inside.

One person held a sign reading "Deny, Defend, Depose," echoing the words written on shell casings and a bullet at the murder scene.

Adam Giesseman, who had a sign that said "Free Luigi" and "Murder for Profit is Terrorism," told ABC News, "Our country is broken.”

Another waiting spectator, who only gave her first name, Natalie, voiced frustration that the insurance system is "set up for profit over people's health."

"It's unfortunate that this happened, and I'm not glorifying it in any way -- but it's brought attention to the issue that affects all Americans," she said.

The 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 added.

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 UnitedHealthcare 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.

Mangione's case in Pennsylvania will be kept active; at the conclusion of his trial in New York, prosecutors would determine how to proceed, Blair County District Attorney Peter Weeks said on Thursday.

Mangione's next hearing in Pennsylvania is scheduled for Feb. 24. This hearing may get postponed or be conducted as a remote Zoom appearance given the impracticality of returning Mangione to Pennsylvania for an in-person hearing, Weeks said.

This is a developing story. Please check back for updates.