Updated

The Ivy League-educated computer programmer charged in the ambush murder of UnitedHealthcare CEO Brian Thompson has been indicted by a New York grand jury.

Luigi Mangione, 26, is accused of sneaking up behind Thompson outside a Manhattan Hilton hotel as the victim, who lived in Minnesota, made his way to a shareholder conference early on the morning of Dec. 4.

Mangione now faces a top charge of first-degree murder, two counts of second-degree murder, seven criminal possession of a weapon charges of various degrees, and criminal possession of a forged instrument, all felonies.

Manhattan District Attorney Alvin Bragg called it a "brazen, targeted and premeditated shooting." Surveillance video shows the assassination-style ambush. A masked man steps out on the sidewalk behind Thompson and opens fire, striking him in the back and walking away.

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Luigi Mangione pictured in a Pennsylvania mugshot after his arrest in connection with the murder of UnitedHealthcare CEO Brian Thompson.

Luigi Mangione pictured in a Pennsylvania mugshot after his arrest in connection with the murder of UnitedHealthcare CEO Brian Thompson. (Obtained by Fox News Digital)

Mangione was arrested in Altoona, Pennsylvania, on Monday, Dec. 9, after people in a McDonald's recognized him from a wanted poster.

He is being held without bail and told a court last week he plans to fight extradition.

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Brian Thompson in a blue button down shirt and blue zip-up smiles for the camera

The CEO of UnitedHealthcare's parent company mourned the killing of Brian Thompson and implored people to see that industry executives are trying their best with a flawed system. (AP Photo/UnitedHealth Group)

Mangione initially faced a range of charges, with second-degree murder as the top charge. In New York, first-degree murder requires special circumstances, such as if the victim is a police officer, the victim was tortured, etc. In this case, prosecutors are now alleging the murder was an act of terrorism.

"This was a killing to invoke terror," Bragg said. "This was not an ordinary killing, not to suggest that any killing is ordinary, but this was extraordinary and the New York State Legislature has set out both the paths, both the murder one and murder two, and this, we allege, is squarely within those statutes which talk about intending to do exactly what we saw happen here."

Authorities say the suspect dropped a burner phone at the scene, and they found fingerprints on other items. They also said they found a ballistic match between Mangione's gun and the rounds that killed Thompson.

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Parts of the suspected murder weapon were 3D printed, including the receiver and a suppressor, according to police. A trio of 9mm bullet casings found at the scene contained the words "defend," "depose" and "deny."

Mangione waited outside the Hilton for about an hour, Bragg said, then allegedly snuck up on Thompson from behind when he saw him approaching the hotel.

Luigi Mangione, the suspect in the murder of United Healthcare CEO, Brian Thompson shouts as he is led into court

Luigi Mangione shouts while officers restrain him as he arrives for his extradition hearing at Blair County Courthouse in Hollidaysburg, Pennsylvania on Tuesday, Dec. 10, 2024. (David Dee Delgado for Fox News Digital)

Thompson, 50, spent 20 years working for UnitedHealth Group and became CEO of the UnitedHealthcare subsidiary in April 2021, according to his online bio. He had two children.

Authorities also slammed online support for the suspect.

"Luigi Mangione is now formally charged and indicted for murder, and let me be perfectly clear, in the nearly two weeks since Mr. Thompson's killing, we have seen a shocking and appalling celebration of cold-blooded murder," NYPD Commissioner Jessica Tisch told reporters. "Social media has erupted with praise for this cowardly attack."

She slammed people who "ghoulishly plastered posters" around the city or came up with a deck of playing cards identifying other CEOs for targeting.

"Let me say this – plainly there is no heroism in what Mangione did," she said. "This was a senseless act of violence. It was a cold and calculated crime that stole a life and put New Yorkers at risk. We don't celebrate murders, and we don't lionize the killing of anyone. And any attempt to rationalize this is a vile, reckless, and offensive to our deeply held principles of justice."

Fox News' Eric Revell contributed to this report.