The man accused of gunning down a US insurance executive in Manhattan—a killing that tapped into widespread anger with the American health care system—appeared in a New York court Thursday to face federal charges including murder.

Luigi Mangione's arraignment took place hours after US television networks broadcast the 26-year-old's dramatic extradition by plane and helicopter from Pennsylvania, where he was arrested at a McDonald's restaurant last week.

Wearing shackles around his ankles, Mangione appeared before federal judge Katharine Parker, who read out the charges in the December 4 shooting of UnitedHealthcare chief executive Brian Thompson, including murder, stalking and firearms offenses, according to a court spokesperson.

Thompson's murder brought to the surface deep public frustration with the dysfunction and ills of the lucrative US commercial health care system, with many social media users lionizing Mangione.

Outside the Manhattan courthouse, supporters held posters that read "Health over wealth" and "Luigi freed us."

But James Dennehy of the FBI New York Field Office stressed that Magione's alleged actions amounted to a "carefully premeditated and targeted execution."

"This alleged plot demonstrates a cavalier attitude towards humanity -- deeming murder an appropriate recourse to satiate personal grievances." 

If convicted, Mangione could face the death penalty or life in prison, the US Department of Justice said.

State charges

The fresh federal charges expand the case against Ivy League graduate Mangione, coming two days after New York prosecutors filed separate state charges against him, including one count of murder in the second degree as "an act of terrorism."

Mangioni's attorney Karen Friedman Agnifilo told reporters she is seeking clarity on how simultaneous federal and state charges would work, calling the situation "highly unusual," CNN reported.

Mangioni's attorneys also said they are not asking the court to release him on bail, at least for now, according to CNN.

Highlighting the intense media attention the case has garnered, multiple television networks boasted live coverage of his trip from Pennsylvania to New York.

Dressed in an orange prison jumpsuit, Mangione left the Pennsylvania courthouse in a black SUV, escorted by police vehicles.

After being flown to an airport outside New York City, he boarded a helicopter to Manhattan, where over a dozen officers, some in tactical gear, waited to retrieve him. 

New York Mayor Eric Adams was among the officials escorting Mangione.

"This act of terrorism and the violence that stems from it is not something that will be tolerated in this city," Adams told reporters. 

Health debate

Mangione was arrested in Altoona, Pennsylvania, on December 9 following a tip from staff at a McDonald's restaurant, after a days-long manhunt. 

Mangione traveled to New York by bus from Atlanta about 10 days before the crime, the Department of Justice said. After checking into a Manhattan hostel with false identification, he allegedly performed reconnaissance near the victim's hotel and the conference venue where the shooting took place.

Early on December 4, Mangione tracked Thompson, walked up behind him and fired several gunshots from a pistol with a silencer, the DOJ said. Afterward, Mangione fled on a bicycle.

Thompson's killing was "a grossly misguided attempt to broadcast Mangione's views across the country," Acting US Attorney Edward Kim for the Southern District of New York said. 

"But this wasn't a debate, it was murder."

Police say a "life-changing, life-altering" back injury may have motivated Mangione, although there was "no indication" he was ever a client of UnitedHealthcare.

When he was arrested, Mangione had a three-page handwritten text criticizing the US health care system, authorities have said.

Reports that the casings of the bullets fired at Thompson had "depose, deny, delay" inscribed on them prompted horror stories on social media about health insurers who allegedly used those very tactics to get out of paying for needed medical care.

Such fights with ailing consumers are only one of the gripes many have with a health system that has also been criticized for mystery billing practices, opaque middlemen, confusing jargon and costly drugs. 

According to the federal charges released Thursday, a notebook found on Mangione had an entry from August saying "the target is insurance" because "it checks every box."