The suspect in the killing of UnitedHealthcare's chief executive struggled with sheriff’s deputies and shouted in an angry outburst as he arrived at court to fight extradition to New York.
Luigi Nicholas Mangione, 26, could be heard shouting words that included “insulting the intelligence of the American people” as he was bundled into a Pennsylvania court by a horde of deputies for the hearing.
Mangione is contesting his extradition back to New York where he has been charged with murder over the shooting of Brian Thompson outside a Manhattan hotel.
He was denied bail at the brief hearing. He has 14 days to challenge the bail decision.
Prosecutors, meanwhile, have a month to seek a governor's warrant out of New York.
Mangione, wearing an orange jumpsuit, mostly stared straight ahead during the hearing, occasionally consulting papers, rocking in his chair, or looking back at the gallery.
At one point, he began to speak to respond to the court discussion, but was told to be quiet by his lawyer.
Thomas Dickey, his defence lawyer, questioned whether the second-degree murder charge filed in New York might be eligible for bail under Pennsylvania law, but prosecutors raised concerns about both public safety and Mangione being a potential flight risk, and the judge denied it.
Prosecutors on Tuesday were beginning to take steps to take Mangione back to New York to face the murder charge while new details emerged about his life and how he was captured.
The Ivy League graduate from a prominent Maryland family was charged with murder hours after he was arrested in the killing of Mr Thompson, 50, who led the United States' largest medical insurance company.
Mr Dickey had declined to comment before the hearing at the Blair County Courthouse in Hollidaysburg.
Mangione is being held without bail in Pennsylvania on charges of possession of an unlicensed firearm, forgery and providing false identification to police. Manhattan prosecutors have charged him with five counts, including murder, criminal possession of a weapon and criminal possession of a forged instrument.
Mangione was likely motivated by his anger with what he called "parasitic" health insurance companies and a disdain for corporate greed, a law enforcement bulletin obtained by The Associated Press said.
He wrote that the US has the most expensive health care system in the world and that profits of major corporations continue to rise while "our life expectancy" does not, according to the bulletin, based on a review of his hand-written notes and social media posts.
Mangione called "Unabomber" Ted Kaczynski a "political revolutionary" and may have found inspiration from the man who carried out a series of bombings while railing against modern society and technology, according to the police bulletin.
Mangione was arrested in Altoona, Pennsylvania - about 230 miles (370km) west of New York City - after a McDonald's customer recognised him and notified an employee, authorities said.
Officers found him sitting at a back table, wearing a blue medical mask and looking at a laptop, according to a Pennsylvania police criminal complaint.
He initially gave them a fake ID, but when an officer asked Mangione whether he had been to New York recently, he "became quiet and started to shake", the complaint says.
When he pulled his mask down at officers' request, "we knew that was our guy," Officer Tyler Frye said.
Images of Mangione released on Tuesday by Pennsylvania State Police showed him pulling down his mask in the corner of the McDonald's while holding what appeared to be hash browns and wearing a winter jacket and beanie. In another photo from a holding cell, he stood unsmiling with rumpled hair.
New York Police Commissioner Jessica Tisch said Mangione was carrying a gun like the one used to kill Mr Thompson and the same fake ID the gunman had used to check into a New York hostel, along with a passport and other fraudulent IDs.
NYPD Chief of Detectives Joseph Kenny said Mangione also had a three-page, handwritten document that shows "some ill will toward corporate America".
A law enforcement official who was not authorised to discuss the investigation publicly and spoke to The Associated Press on condition of anonymity said the document included a line in which Mangione claimed to have acted alone.
"To the Feds, I'll keep this short, because I do respect what you do for our country. To save you a lengthy investigation, I state plainly that I wasn't working with anyone," the document said, according to the official.
It also had a line that said: "I do apologise for any strife or traumas but it had to be done. Frankly, these parasites simply had it coming."
Pennsylvania prosecutor Peter Weeks said in court that Mangione was found with a passport and 10,000 dollars (£7,839) in cash, 2,000 dollars of it in foreign currency. Mangione disputed the amount.
Mr Thompson was killed on Wednesday as he walked alone to a Manhattan hotel for an investor conference. Police quickly came to see the shooting as a targeted attack by a gunman who appeared to wait for Mr Thompson, came up behind him and fired a 9mm pistol.
Investigators have said "delay," "deny" and "depose" were written on ammunition found near Mr Thompson's body. The words mimic "delay, deny, defend," a phrase used to criticise the insurance industry.
From surveillance video, New York investigators determined the gunman quickly fled fled the city, likely by bus.
A grandson of a wealthy, self-made real estate developer and philanthropist, Mangione is a cousin of a current Maryland state legislator.
After his elite Baltimore prep school, he went on to earn undergraduate and graduate degrees in computer science in 2020 from the University of Pennsylvania, a spokesperson said.
"Our family is shocked and devastated by Luigi's arrest," Mangione's family said in a statement posted on social media late Monday by his cousin, Nino Mangione.
"We offer our prayers to the family of Brian Thompson and we ask people to pray for all involved."
From January to June 2022, Luigi Mangione lived at Surfbreak, a "co-living" space at the edge of Waikiki in Honolulu.
Like other residents of the shared penthouse catering to remote workers, Mangione underwent a background check, said Josiah Ryan, a spokesperson for owner and founder RJ Martin.
"Luigi was just widely considered to be a great guy. There were no complaints," Mr Ryan said. "There was no sign that might point to these alleged crimes they're saying he committed."
At Surfbreak, Mr Martin learned Mangione had severe back pain from childhood that interfered with many aspects of his life, from surfing to romance, Ryan said.
"He went surfing with RJ once but it didn't work out because of his back," Mr Ryan said, but noted that Mangione and Mr Martin often went together to a rock-climbing gym.
Mangione left Surfbreak to get surgery on the mainland, Mr Ryan said, then later returned to Honolulu and rented an apartment.
Mr Martin stopped hearing from Mangione six months to a year ago.
