Luigi Mangione agreed to go back to New York after a morning court appearance in Pennsylvania where he was arrested last week after five days on the run. He was expected in a Manhattan federal court in the afternoon.

After his Pennsylvania court appearance, he was immediately turned over to at least a dozen New York Police Department officers who were in the courtroom and quickly led him to a plane bound for Long Island.

He then was taken away by helicopter to Manhattan.

The federal complaint unsealed on Thursday charges him with two counts of stalking and one count each of murder through use of a firearm and a firearms offence.

A courtroom had been set aside in a Manhattan federal courthouse for Mangione's hearing.

Blair County District Attorney Pete Weeks said on Thursday that he wanted to turn Mangione over to New York authorities as soon as possible.

"He is now in their custody. He will go forth with New York to await trial or prosecution for his homicide and related charges in New York," Mr Weeks said.

The 26-year-old Ivy League graduate is accused of ambushing and shooting Brian Thompson on December 4 outside a Manhattan hotel where the head of the United States' largest medical insurance company was walking to an investor conference.

Authorities have said Mangione was carrying the gun used to kill Mr Thompson, a passport, fake IDs and about 10,000 US dollars (£7,900) when he was arrested while eating breakfast on December 9 at a McDonald's in Altoona, Pennsylvania.

Mangione, who initially fought attempts to extradite him, made two brief court appearances on Thursday, first waiving a preliminary hearing on forgery and firearms charges before agreeing to be sent back to New York.

The state charges there against him include murder as an act of terrorism. He could face life in prison without parole if he's convicted.

Investigators believe Mangione was motivated by anger toward the US health care system and corporate greed. But he was never a UnitedHealthcare client, according to the insurer.

According to the federal complaint unsealed on Thursday, a notebook Mangione was carrying when he was arrested included several handwritten pages expressing hostility toward the health insurance industry and wealthy executives in particular.

An August entry said that "the target is insurance" because "it checks every box", according to the filing.

An entry in October "describes an intent to 'wack' the CEO of one of the insurance companies at its investor conference", the document said.

The killing ignited an outpouring of stories about resentment toward US health insurance companies while also shaking corporate America after some social media users called the shooting payback.

Video showed a masked gunman shooting Mr Thompson, 50, from behind and then firing several more shots.

The suspect eluded police despite authorities widely circulating photos of his unmasked face until Mangione was captured in Altoona, about 277 miles west of New York.

Mangione, a computer science graduate from a prominent Maryland family, was carrying a handwritten letter that called health insurance companies "parasitic" and complained about corporate greed, according to a law enforcement bulletin obtained by the Associated Press last week.

One of his lawyers has cautioned the public against prejudging the case.

Mangione repeatedly posted on social media about how spinal surgery last year had eased his chronic back pain, encouraging people with similar conditions to speak up for themselves if told they just had to live with it.

In a Reddit post in late April, he advised someone with a back problem to seek additional opinions from surgeons and, if necessary, say the pain made it impossible to work.

"We live in a capitalist society," Mangione wrote. "I've found that the medical industry responds to these key words far more urgently than you describing unbearable pain and how it's impacting your quality of life."

He apparently cut himself off from his family and close friends in recent months. His family reported him missing in San Francisco in November. His relatives have said in a statement that they were "shocked and devastated" by his arrest.

Mr Thompson, who grew up on a farm in Iowa, was trained as an accountant.

A married father of two high-schoolers, he had worked at the giant UnitedHealth Group for 20 years and became chief executive of its insurance arm in 2021.