Luigi Mangione indicted by New York grand jury for murdering UnitedHealthcare CEO

"The unsealing of today’s indictment brings us one step closer to securing justice for Brian Thompson and his family and affirming the primacy of the rule of law in the city of New York," said Commissioner Jessica Tisch of the New York Police Department at a news conference.

The grand jury issued the 11-count indictment earlier this month, which includes one count of first-degree murder and two counts of second-degree murder in addition to weapon and forgery charges.

The second-degree murder charges were handed down because the grand jury classified the killing as a crime of terrorism, according to the criminal complaint.

"This was a frightening, well-planned, targeted murder that was intended to cause shock and attention and intimidation," Manhattan District Attorney Alvin Bragg told reporters.

"It incurred in one of the most bustling parts of our city, threatening the safety of local residents and tourists alike, and commuters and businesspeople just starting out on their day," Bragg added.

Mangione, 26, was arrested in the state of Pennsylvania. But his attorney, Karen Friedman Agnifilo, told CNN that her client is not going to fight extradition to New York when he appears Thursday at his scheduled court hearing.

Investigators believe that Mangione premeditated the murder because he was angry at the US health care system and its "corporate greed."

When police arrested him, they found a 3D-printed ghost gun, a fake ID, and a handwritten document that criticized the health care industry with a passage that said "frankly these parasites had it coming."

Mangione's Pennsylvania attorney, Thomas Dickey, told news outlets that his client would be pleading not guilty to all counts in both New York and Pennsylvania, although his New York attorney, Friedman Agnifilo, has not yet confirmed whether that will be the case moving forward with the court proceedings.