Luigi Mangione admitted on Friday to gunning down a top US health insurance boss in a Manhattan street as he pleaded guilty to stalking charges before a federal judge.

In a crime that shook corporate America and gripped the country, 28-year-old Mangione is alleged to have shot dead chief executive of UnitedHealthcare Brian Thompson, 50, in December 2024 to protest the US insurance system.

“On the morning of December 4, I shot Mr Thompson in Manhattan and he died,” Mangione told a federal judge as he pleaded guilty to stalking his victim. He will be sentenced on December 18 and prosecutors said they would seek a life term.

He had been facing the stalking charges in the federal system, alongside murder charges in the New York state system but Mangione’s lawyers called on Friday for the state charges to be dropped to prevent him being prosecuted twice for the same conduct.

“We just filed our motion in state court, explaining why the state charges must be dismissed under New York’s double jeopardy protections,” said Mangione’s lawyer Karen Friedman Agnifilo.

The stalking charges and the murder charges could both lead to life sentences. Two other federal charges that carried the death penalty were thrown out by a judge earlier this year.

The case has sharply divided already polarized public opinion, with conservatives led by US President Donald Trump calling for an example to be made of Mangione.

Prosecutors on Friday said he deserved heavy punishment.

“There can be no celebrity in assassination,” Jamie McDonald, the US attorney for the Southern District of New York, told reporters.

But ardent supporters of Mangione flocked to the Manhattan courthouse to show their support amid heavy security as a helicopter hovered overhead.

Relatives of Thompson were reportedly in court for the hearing, and a man shouted “America loves Luigi” at them as they left in a convoy of black SUVs.

Insurance industry frustration

Thompson’s murder unsurfaced deep public frustration with the lucrative US commercial health care system, with some social media users painting Mangione as a hero.

He was arrested in Altoona, Pennsylvania, on December 9 following a tip from staff at a McDonald’s restaurant, after a days-long manhunt.

He had travelled to New York by bus from Atlanta about 10 days before the crime, US prosecutors said.

After checking into a Manhattan hostel with false identification, he allegedly performed reconnaissance near the victim’s hotel and the conference venue where the shooting took place.

Following his arrest, officers strip-searched him and went through property that included a handgun, a silencer and a jar of Skippy peanut butter.

Mangione also admitted in court on Friday that he used a 3-D printer to make a gun and equipped it with a silencer and magazine.

A checklist also found on Mangione contained entries including “intel check in” and reminders to purchase a camera from the Best Buy retail chain.

Defendants in the United States can be tried at both the state and federal level for the same crime, although the charges tend to differ — as they do for Mangione.