NEW YORK — The man accused of killing UnitedHealthcare’s CEO has been charged with murder as an act of terrorism, prosecutors said Tuesday as they worked to bring him to a New York court from a Pennsylvania jail.

Luigi Mangione already was charged with murder in the Dec. 4 killing of Brian Thompson, but the terror allegation is new.

Manhattan District Attorney Alvin Bragg said Thompson’s death on a midtown Manhattan street “was a killing that was intended to evoke terror. And we’ve seen that reaction.”

“This was a frightening, well-planned, targeted murder that was intended to cause shock and attention and intimidation,” he said at a news conference Tuesday. “It occurred in one of the most bustling parts of our city, threatened the safety of local residents and tourists alike, commuters and businesspeople just starting out on their day.”

Mangione’s New York lawyer, Karen Friedman Agnifilo, declined to comment.

Thompson, 50, was shot while walking to a hotel where Minnesota-based UnitedHealthcare — the United States’ biggest medical insurer — was holding an investor conference.

The killing kindled a fiery outpouring of resentment toward U.S. health insurance companies, as Americans swapped stories online and elsewhere of being denied coverage, left in limbo as doctors and insurers disagreed, and stuck with sizeable bills.

The shooting also rattled C-suites, as “wanted” posters with other health care executives’ names and faces appeared on New York streets. An outpouring of online vitriol prompted police to warn that there could be an “elevated threat.”

A New York law passed after the Sept. 11 attacks allows prosecutors to charge crimes as acts of terrorism when they’re “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.”

Prosecutors have used the statute in a variety of contexts.

Its first use was against a Bronx gang member charged in a hail of gunfire that killed a 10-year-old girl and paralyzed a man outside a christening party in 2002. Prosecutors said that shooting was part of a campaign of gang intimidation in a neighborhood.

The state’s highest court later said the conduct didn’t amount to terrorism, threw out the conviction and ordered a new trial. The defendant, who denied involvement in the shooting, was retried, convicted of attempted murder and manslaughter and sentenced to 50 years in prison.

In the Thompson case, after days of intense police searches and publicity, Mangione was spotted at a McDonald’s in Altoona, Pennsylvania, and arrested. New York police officials have said Mangione was carrying the gun used to kill Thompson, a passport and various fake IDs, including one that the suspected shooter presented to check into a New York hostel.

The 26-year-old was charged with Pennsylvania gun and forgery offenses and locked up there without bail. His Pennsylvania lawyer has questioned the evidence for the forgery charge and the legal grounding for the gun charge. The attorney also has said Mangione would fight extradition to New York.

Mangione has two court hearings scheduled for Thursday in Pennsylvania, including an extradition hearing, Bragg noted.

Hours after his arrest, the Manhattan district attorney’s office filed paperwork charging him with murder and other offenses. The indictment builds on that paperwork.

Investigators’ working theory is that Mangione, an Ivy League computer science grad from a prominent Maryland family, was propelled by anger at the U.S. health care system. A law enforcement bulletin obtained by The Associated Press week said that when arrested, he was carrying a handwritten letter that called health insurance companies “parasitic” and complained about corporate greed.