Luigi Mangione pleads not guilty to 'terrorist' murder of healthcare CEO

Luigi Mangione, accused of gunning down a health insurance executive in a brazen hit in New York, has pleaded not guilty to state charges, including "terrorist" murder.

Mangione, 26, was escorted on Monday into Judge Gregory Carro's 13th-floor courtroom in the New York state criminal courthouse in lower Manhattan with a court officer on each arm, and a procession of a half dozen officers following him. He was in handcuffs and shackles, and wore a burgundy sweater over a white-collared shirt.

Mangione leaned into a microphone and said "not guilty" when Carro asked how he pleaded to the 11-count indictment charging him with murder as an act of terrorism and weapons offences.

The suspect is charged in both state and federal court in the December 4 shooting of UnitedHealthcare chief executive Brian Thompson.

If convicted, he faces a maximum sentence of life in prison without the possibility of parole.

After the 30-minute hearing, officers once again shackled Mangione and led him out of the courtroom. He is being held at the Metropolitan Detention Center, a federal lockup in Brooklyn.

Carro set Mangione's next court appearance for February 21.

'Political fodder'

Thompson's murder brought to the surface deep public frustration with the lucrative US commercial healthcare system, with many social media users painting Mangione as a hero.

That spectacle and other statements by public officials suggest Mangione may not be able to get a fair trial, his lawyer Karen Friedman Agnifilo said at Monday's hearing.

"They are treating him like he is some sort of political fodder, some sort of spectacle," Agnifilo said. "He is not a symbol, he is someone who is afforded a right to a fair trial."

Several dozen people gathered outside the courthouse in freezing temperatures to express support for Mangione and anger at healthcare companies.

One person held a sign with the words "DENY, DEFEND, DEPOSE," a phrase that echoes tactics some accuse insurers of using to avoid paying out claims.

Authorities say the words "deny," "delay," and "depose " were found written on shell casings at the crime scene.

Kara Hay, a 42-year-old schoolteacher, said she believed it was wrong for Mangione to be charged with terrorism.

"Shooting one CEO does not make him a terrorist, and I do not feel terrorised," said Hay, who held a sign reading "innocent until proven guilty."

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