Luigi Mangione, the man accused of fatally gunning down UnitedHealth Group chief executive Brian Thompson on a Manhattan street, pleaded not guilty on Monday to state murder charges that brand him a terrorist.

The 11-count indictment includes three murder charges, including murder as an act of terrorism. If convicted, he faces a maximum sentence of life in prison without the possibility of parole.

Monday’s arraignment at New York state criminal court in Manhattan was the second court appearance in New York for Mangione, 26, since he was arrested at a McDonald’s restaurant in Altoona, Pennsylvania, five days after the brazen, pre-dawn December 4 killing of Thompson outside a hotel in midtown Manhattan where his company was gathering for an investor conference.

Mangione also faces a four-count federal criminal complaint charging him with stalking and killing Thompson.

He has not yet been asked to enter a plea to those charges.

US Magistrate Judge Katharine Parker ordered Mangione detained at a Dec 19 presentment on those charges.

More than two dozen members of the public sat in the audience of the courtroom where Mangione was presented.

A small group of protesters had gathered outside the lower Manhattan courthouse in sub-freezing temperatures expressing support for Mangione and anger at healthcare companies.

One person held a sign saying: “Deny, defend, depose,” the words police say were found etched on shell casings at the crime scene.

The words echo tactics some accuse insurers of using to avoid paying out claims.

While the killing of Thompson has been condemned by public officials, Mangione has been feted as a folk hero by some Americans who decry the steep costs of healthcare and the power held by insurance companies to deny paying for some medical treatments.

A notebook entry

The federal charges would make him eligible for the death penalty, should the US attorney’s office in Manhattan decide to pursue it.

The separate federal and state cases will proceed in parallel. The state case is currently expected to go to trial first, federal prosecutors said.

Mangione’s lead lawyer, Karen Friedman Agnifilo, said at the federal court hearing that the two sets of charges appeared to be based on conflicting theories.

The state charges accuse Mangione of intending to “intimidate or coerce a civilian population” and influence policy, while the federal charges accuse him of stalking and killing an individual.

Agnifilo said the two cases seemed completely different, and she asked prosecutors to clarify whether both would continue.

Dominic Gentile, a federal prosecutor, said Thursday’s initial appearance was not the appropriate time to address those legal arguments.

According to the federal criminal complaint, the police who arrested Mangione found a notebook that contained several handwritten pages that “express hostility towards the health insurance industry and wealthy executives in particular”.

A notebook entry dated October 22 allegedly described an intent to “wack” the chief executive of an insurance company at its investor conference.