Police on Monday arrested 26-year-old Luigi Mangione, who they believe is a strongman in connection with the fatal shooting of UnitedHealthcare CEO Brian Thompson last week.

Police in Altoona, Pennsylvania, arrested Mangione for weapons possession after discovering he had a gun, a fake New Jersey ID card with the same ID the suspect used to check into a New York City hostel, and an ID card with his had real name.

In addition to the gun and fake ID, police also found a three-page handwritten note about Mangione in which he appeared to express “dislike of the American economy,” New York Police Department Chief Detective Joseph Kenny said at a news conference Monday.

The document “shows both his motivation and his attitude,” NYPD Commissioner Jessica Tisch said at the news conference.

CNN quoted a law enforcement source as saying the author of the documents apologized for “any strife or trauma,” but added: “These parasites had it under control.”

The New York Times also quoted a senior law enforcement official as saying that the manifesto found on Mangione mentioned UnitedHealthcare by name and mentioned the size of the company and how much money it made. The official added that the document condemns the healthcare industry for prioritizing profits over care.

Mangione was arraigned on the weapons charges in Pennsylvania on Monday evening. According to court documents filed in Blair County, he was charged with forgery, carrying a firearm without a license, tampering with records or identification, possession of instruments of crime and presenting false identification to law enforcement.

He has not been charged with Thompson’s murder and cannot be charged until he is in New York.

Thompson, 50, was shot last week while on his way to an annual investor conference at the Hilton Hotel in midtown Manhattan. The shooting sparked a nationwide manhunt that captured public interest and reignited the debate over access to health care.

Police released several images of the suspected shooter and arrested Mangione Monday morning at a McDonald’s in Altoona, Pennsylvania, after a restaurant employee thought Mangione was suspicious and called authorities.

According to court documents filed Monday, Mangione began shaking as he was being questioned by police.

Mangione gave a responding officer a New Jersey driver’s license with a different name, the criminal complaint states. Then, when another officer asked Mangione if he had been in New York recently, “Mangione became quiet and began shaking,” the complaint says.