Luigi Mangione, the suspect in the killing of UnitedHealthcare executive Brian Thompson, has appeared in a New York court to face new federal charges including murder and stalking.

Mangione’s arraignment on Thursday followed his transfer to New York from Pennsylvania after he waived his right to extradition proceedings.

Shackled at the ankles and wearing a blue sweater and beige slacks, Mangione said little during a 15-minute appearance before United States Magistrate Judge Katharine Parker in Manhattan.

The 26-year-old Ivy League graduate, who was already facing multiple state charges, was charged with murder using a firearm, two counts of stalking and using an illegal gun silencer, according to an unsealed criminal complaint.

The federal charges raised the possibility that Mangione could face the death penalty, if prosecutors seek it.

Mangione’s lawyer, Karen Friedman Agnifilo, said it was a “highly unusual situation” for a defendant to face simultaneous state and federal cases.

“Frankly I’ve never seen anything like what is happening here,” Friedman Agnifilo said.

According to the criminal complaint, Mangione traveled from Georgia to New York “for the purpose of stalking and killing Brian Thompson”.

A notebook found in Mangione’s possession after his arrest at a McDonald’s outlet in Altoona, Pennsylvania contained several handwritten pages that “express hostility towards the health insurance industry and wealthy executives in particular”, according to the complaint.

An entry in August said that “the target is insurance” because “it checks every box”, while an October entry described an intent to “wack” the CEO of an insurance company”, according to the complaint.

Police say the words “delay,” “deny” and “depose” were scrawled on shell casings found at the murder scene, recalling a phrase commonly used to describe insurer tactics to avoid paying claims.

As Mangione was arraigned in court, supporters gathered outside holding posters that read “Health over wealth” and “Luigi freed us”.

James Dennehy of the FBI New York Field Office said 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,” Dennehy said.