Charges filed for the brutal murder of a Manhattan CEO

According to the indictment, Mangione was also charged with possession of a loaded firearm, possession of a forged document - a fake driver's license that he allegedly used to apply to stay at a hostel in New York, and criminal possession of a weapon.

He will remain in the custody of the Pennsylvania Department of Corrections pending his extradition to New York.

The indictment in New York came hours after Mangione was arrested in Altoona, Pennsylvania. He was identified by a McDonald's employee based on photos released by police of the suspect in the Dec. 4 shooting death of Brian Thompson in midtown Manhattan.

Thompson, who became UnitedHealthcare's chief insurance executive in April 2021, was shot in the back in a targeted attack by a masked assailant shortly before the company's annual investor conference at the Hilton Hotel on Sixth Avenue in New York.

Mangione is charged with five felonies, including carrying a weapon without a license, forgery, making false representations to authorities and possession of what is believed to be a silenced handgun in the commission of a crime, according to the Pennsylvania criminal complaint.

During a search of Mangioni's backpack after his arrest, officers allegedly found a black 3D-printed handgun and a black silencer, which was also 3D-printed, according to the criminal complaint.

NYPD Chief of Detectives Joe Kenny described the weapon allegedly found in Mangione's possession as a "ghost gun," meaning it has no serial number and cannot be traced.

Several handwritten pages were also found on Mangione during his arrest, which Kenney said contained text expressing "some ill will toward corporate America" ​​and mentioned UnitedHealthcare by name, law enforcement sources told ABC News.

Police are investigating Mangione's travel to various locations across the United States and outside the county over the past year, sources said.