NEW YORK (AP) -- The man accused of gunning down United Healthcare's CEO outside a Manhattan hotel is now in a federal jail in New York, after he was returned to the city in dramatic fashion to face charges that could bring the death penalty.

Shackled and wearing an orange prison jumpsuit, 26-year-old Luigi Mangione was escorted Thursday by a contingent of heavily armed police officers as he was whisked by plane and then helicopter from Pennsylvania to downtown Manhattan.

The Ivy League graduate, who prosecutors say inveighed against the health insurance industry and wealthy executives in his writings, then appeared in a packed federal courtroom on murder, stalking and firearms charges in the Dec. 4 killing of Brian Thompson. He was not required to enter a plea.

Here's what's next in the case:

Mangione is being held without bail at Metropolitan Detention Center, the same federal jail where hip-hop mogul Sean "Diddy" Combs and cryptocurrency fraudster Sam Bankman-Fried are currently detained.

The notorious Brooklyn facility, the only federal lockup in the city, has been variously described as "hell on earth" and an "ongoing tragedy" because of deplorable conditions, rampant violence, dysfunction and multiple deaths.

The federal Bureau of Prisons has said it is increasing staffing to make up for staggering shortfalls, but conditions have been so stark at the jail, which houses about 1,100 inmates, that some judges have refused to send people there.

Besides the federal charges filed Thursday, Mangione must still answer to a state murder indictment.

Manhattan District Attorney Alvin Bragg's office charged Mangione with murder as an act of terrorism, which carries a maximum sentence of life in prison without parole. He is also charged with state weapons offenses and possession of a fake ID.

Prosecutors have said the two cases will proceed on parallel tracks, with the state charges expected to go to trial first.

Mangione's lawyer, Karen Friedman Agnifilo, argued in court Thursday that the terrorism allegations in the state case and stalking charges in the federal complaint appear to be at odds.

"Those are two completely different theories," she said. "These seem like different cases."

The U.S. Supreme Court in 2019 upheld a longstanding constitutional rule allowing state and federal governments to prosecute someone for the same crime.

It's still not clear when Mangione will be arraigned on the state indictment.

Spokespersons for the state courts and Bragg's office didn't have any updates Friday.

The University of Pennsylvania alum, who hailed from a prominent Maryland family and had also lived in Hawaii, had been expected to be arraigned Thursday on the state charge before the federal charges preempted that appearance.

In the federal case, Mangione could next return to court for a bail hearing or for a preliminary hearing if prosecutors don't obtain a grand jury indictment by mid-January.

New York effectively effectively abolished its death penalty by 2007 and the last execution in the state was in 1963. But the federal death penalty remains in effect.

The federal complaint filed against Mangione includes a count of murder by firearm, which carries the possibility of the death penalty if he is convicted.

Federal prosecutors have not said if they will seek the death penalty. That decision will be made in coming months by Justice Department officials in Washington, likely after President-elect Donald Trump is sworn in on Jan. 20.

President Joe Biden's administration put a moratorium on federal executions soon after he took office in 2021, but that hasn't stopped federal prosecutors from seeking the death penalty.

In contrast, Trump's administration carried out 13 executions in the last six months of his first term.

Mangione also faces forgery and firearms charges in Pennsylvania stemming from his arrest last week, but those will likely not be addressed until the New York charges are resolved.

He initially fought attempts to be returned to New York, but ultimately waived extradition and a preliminary hearing on the Pennsylvania charges on Thursday.

"He is now in their custody," Blair County District Attorney Peter Weeks said after Mangione was extradited to New York. "We intend to keep our case active and we intend to essentially revisit the case when the defendant is available for prosecution in Blair County."

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Associated Press reporter Larry Neumeister in New York contributed to this story.

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Follow Philip Marcelo at twitter.com/philmarcelo.