The alleged killer of UnitedHealthcare CEO Brian Thompson, Luigi Mangione, has been indicted by a New York grand jury on charges of murder.

Mangione, 26, has been charged with one count of murder in the first degree and two counts of murder in the second degree.

He is also charged in Manhattan supreme court with multiple counts of criminal possession of a weapon and a single count of criminal possession of a weapon in the second degree.

After Mangione’s arrest earlier this month, prosecutors had filed a criminal complaint against him charging him with second-degree murder, criminal possession of a loaded firearm, possession of a silencer and possession of a forged instrument. This indictment supersedes that complaint.

The Manhattan district attorney, Alvin Bragg, said in a statement that Mangione had allegedly “carried out the brazen, targeted and fatal shooting” and that “this type of premeditated, targeted gun violence cannot and will not be tolerated, and my office has been working day in and day out to bring the defendant to justice”.

Mangione’s lawyer, Karen Friedman Agnifilo, told CNN that Mangione does not plan to fight his upcoming extradition to New York. He is being held without bail and expected in a Blair county court in Pennsylvania on Thursday for an extradition hearing.

A conviction of second-degree murder in New York would see Mangione serving 15 years to life in prison; a first-degree murder conviction would see a sentence of 20 years to life.

The New York City police commissioner, Jessica Tisch, lambasted Mangione’s supporters at a news conference on Tuesday.

“Let me say plainly: there is no heroism in what Mangione did,” Tisch said. “We don’t celebrate murders.”

In the immediate aftermath of Thompson’s killing, many Americans defended Mangione’s alleged actions because they viewed Thompson – the CEO of a major healthcare insurer – as complicit in denying or deferring what they saw as needed care. While others have spoken out against the act of allegedly killing a father of two in cold blood, Mangione has been hailed as a Marxist folk hero and a “hot assassin”, among many other titles.

Thompson, 50, was killed at gunpoint on 4 December in midtown Manhattan as he was walking to attend UnitedHealthcare’s annual investors’ meeting.

The suspect escaped the scene and fled on foot, later by ebike, to Central Park. After several days of a search in New York City, Mangione was found and reported to police while in a McDonald’s in Altoona, Pennsylvania, on 9 December. Police found Mangione in possession of a firearm suppressor, a mask consistent with that worn by the gunman, a fraudulent New Jersey ID matching the ID the man used to check into a New York City hostel before the shooting, and a handwritten document.