• Luigi Mangione is in New York to face both state and federal murder charges.
• His new federal indictment alleges he stalked and then killed UnitedHealthcare CEO Brian Thompson.
• Manhattan prosecutors say state charges will "proceed in parallel with any federal case."

Luigi Mangione appeared in federal court Thursday on new federal murder charges that could result in the death penalty or life in prison.

It was Mangione's first appearance in a Manhattan courtroom, this one crowded with press and federal staff, on charges in the shooting death of UnitedHealthcare CEO Brian Thompson. He is expected to be arraigned on state murder charges in a courthouse one block away on Friday.

Mangione's voice was calm but firm as he answered the judge's questions.

"Mr. Mangione, do you understand what you have been accused of?" US Magistrate Judge Katharine H. Parker asked at one point before he entered his plea.

"Yes," he answered.

Edward Y. Kim, the acting US attorney for the Southern District of New York, has yet to say if he will seek the death penalty or a life sentence for the most serious charge in the four-count indictment — murder through the use of a firearm.

One former federal prosecutor called the death penalty a "remote" possibility, given Mangione's youth, and the chance that he may have suffered a mental breakdown in the six months before the shooting.

"In New York's federal courts, it's uncommon for them to seek the death penalty, and I think probably more uncommon for juries to want to authorize it, even assuming that Mr. Mangione killed Mr. Thompson in the way the government is alleging," said Michael Bachner, now in private practice.

The other three federal counts against Mangione allege he possessed and used an illegal firearm, and that he traveled interstate — between Georgia and New York, in order to stalk and kill Thompson.

Mangione presented an orderly, if tense, appearance in the chilly 26th-floor courtroom.

He was clean-shaven and his bushy eyebrows neatly groomed. Mangione sat with his shoulders raised and held stiff and wore khaki pants and a navy quarter-zip sweater over a white collared button-down shirt.

His ankles were shackled together with thick chains beneath the table where he sat. He wore bright orange slip-on sneakers without shoelaces.

To either side of Mangione sat his lawyers, husband-wife legal team Karen Friedman Agnifilo and Marc Agnifilo. Both are veteran criminal attorneys and former prosecutors. Their firm, Agnifilo Intrater, LLC, also represents Sean "Diddy" Combs in his federal sex-trafficking case, scheduled to be tried in the same Manhattan courthouse in May.

After Parker read the charges aloud to him, Mangione's posture relaxed. He repeatedly raised his left hand to pat down the hair at the back and side of his head.

He crossed his arms and wore a skeptical expression on his face with his tongue poking out between his lips while Friedman Agnifilo demanded clarity on how different law enforcement agencies coordinated and would present evidence in the case.

Mangione's next court date was set for January 18. His lawyers did not apply for bail, though Friedman Agnifilo said in court that she may do so on a future date.

Earlier Thursday, in a Pennsylvania courtroom, Mangione abandoned his extradition fight and was whisked to New York in an NYPD aviation plane and, upon landing at a Long Island airport, via police chopper to a lower Manhattan heliport.

His arrival in federal court was greeted by dozens of reporters and a smattering of fans holding messages of support written on cardboard.

"Health over Wealth," read one.

Mangione has yet to be arraigned on his first murder case, announced Tuesday by Manhattan District Attorney Alvin Bragg.

He faces up to life in prison on that state indictment, which alleges he murdered Thompson as an act of terror — a first-degree felony, the highest state charge and penalty available.

In a press statement after Mangione's federal appearance, Kim said he expects the state case — announced by Bragg just two days prior — would proceed to trial first.

In court Thursday, Friedman Agnifilo called the dual prosecutions "highly unusual" and said the charges between the Manhattan district attorney's office and the federal US attorney's office seemed to contradict each other.

The district attorney's indictment alleges Mangione killed Thompson in furtherance of "terrorism" that affects a "population of people," she said. But the federal charges accuse Mangione of stalking Thompson as an individual, she said.

Police and prosecutors say Mangione killed Thompson outside a midtown Manhattan hotel on December 4.

Mangione was arrested in Altoona, Pennsylvania, after a five-day manhunt, on local gun and false ID charges. A Manhattan grand jury later indicted on charges related to the killing itself, and the New York cases will take priority over the lesser charges in Pennsylvania.

While in jail in Pennsylvania, Mangione received 54 email messages and 87 pieces of mail, Maria Bivens, of the state Department of Corrections, told BI.

There were also 163 deposits made into Mangione's commissary account, Bivens said. Bivens declined to say how much money was deposited in total.

These accounts can be used to buy toiletries or additional food items in the jail's store.