Manhattan District Attorney Alvin Bragg announced Tuesday Luigi Mangione has been charged with first-degree murder in the fatal shooting of UnitedHealthcare CEO Brian Thompson.

It's unusual to be charged with first-degree murder in the state of New York -- the charge is usually reserved for cases involving the killing of law enforcement officers and for acts of terrorism. Mangione had been facing a preliminary charge of second-degree murder after he was arrested last week.

First-degree murder sentences typically involve life without parole due to the element of premeditated intent. In contrast, second-degree murder might result in a 15-year-to-life sentence, where parole might be an eventual possibility.

According to the indictment, obtained by TMZ ... Mangione allegedly killed Thompson "in furtherance of an act of terrorism ... intended to intimidate or coerce a civilian population, influence the policies of a unit of government by intimidation or coercion, and affect the conduct of a unit of government by murder, assassination or kidnapping."

The indictment notes a grand jury accuses the defendant, Mangione, of the crime.

The terrorism angle would seem to match up with the purported manifesto Mangione allegedly had in his possession when he was arrested at an Altoona, Pennsylvania McDonald's last week, following a week-long manhunt. The manifesto is said to contain criticism of the healthcare system.

And shell casings found at the murder scene were engraved with the words "Deny, Depose, Defend" -- an apparent reference to a book about the industry's practices. Many people have interpreted these details as making a political statement.

The second count in the indictment is a charge of murder in the second degree as a crime of terrorism. The third count is murder in the second degree. The fourth and fifth counts are criminal possession of a weapon in the second degree. The sixth, seventh, eighth, and ninth counts is criminal possession of a weapon in the third degree. The tenth count is criminal possession of a weapon in the fourth degree. And the eleventh count is criminal possession of a forged instrument in the second degree.