Luigi Mangione pleaded guilty Friday to two federal stalking charges connected to the 2024 killing of UnitedHealthcare CEO Brian Thompson, a major development that could complicate New York prosecutors’ separate murder case against him.

Mangione, 28, not only pleaded guilty in Manhattan federal court to two stalking charges resulting in Thompson’s death, but he also admitted to killing him two years ago on Dec. 4, 2024. Each count carries a maximum sentence of life in prison.

“I shot Mr. Thompson in Manhattan,” Mangione told the court on Friday. “I understood that my actions would place him in fear of death or bodily injury. I knew what I was doing was illegal.”

The plea came weeks before Mangione was scheduled to stand trial in New York state court on charges including second-degree murder in the Dec. 4, 2024, shooting of Thompson outside a Midtown Manhattan hotel.

Federal prosecutors initially brought additional murder and firearms charges, and then-Attorney General Pam Bondi directed prosecutors to seek the death penalty. But U.S. District Judge Margaret Garnett dismissed the death-eligible counts in January, leaving the two stalking charges.

At a news conference after the hearing, Southern District of New York prosecutors said the office had “consistently pursued the maximum penalties under the law” and that Mangione’s open plea permits it to seek life imprisonment.

Meanwhile, his defense lawyer, Karen Friedman Agnifilo, said outside the courthouse that Mangione’s defense team plans to raise a double-jeopardy challenge in the state case. She subsequently filed a motion in state court seeking the Manhattan DA’s Office to drop the state case against her client.

The failed death penalty effort has also given Mangione’s lawyers an opening to exploit an unusual federal prosecution, former federal prosecutor Neama Rahmani said. Federal authorities typically do not bring murder cases when state prosecutors are already handling them, he told LiveNOW from Fox, but the remaining stalking charges could now be used to challenge Manhattan District Attorney Alvin Bragg’s state case on double-jeopardy grounds.

How long could Mangione face in prison?

The Department of Justice did not negotiate a plea agreement ahead of time in connection with Friday’s hearing. Instead, Mangione pleaded open to all pending counts, meaning there were “no accommodations or concessions,” prosecutors said.

Mangione now faces a statutory maximum sentence of life in federal prison, though the court will set his punishment at a later hearing after receiving recommendations from prosecutors, his lawyers, and the U.S. Probation Office. Prosecutors said they intend to seek life imprisonment, while Garnett will make the ultimate sentencing decision. Sentencing is scheduled for Dec. 18.

The federal case has drawn unusual attention because it overlaps with the state prosecution, which is scheduled to begin next month. State prosecutors have accused Mangione of second-degree murder, a charge that carries a possible sentence of 25 years to life.

In pleading guilty, Mangione admitted to stalking Thompson before shooting him as the executive walked to a UnitedHealth Group investor conference. He had pleaded not guilty in both the federal and state cases before Friday’s hearing.

Thompson’s family and many of his friends were in court for the guilty plea, SDNY prosecutors said, adding that they will have an opportunity to be heard at sentencing.

State murder trial faces new uncertainty

Mangione’s guilty plea is expected to trigger a renewed fight over whether New York can proceed with its murder case.

New York’s double-jeopardy protections can be broader than the federal Constitution’s protections. Although federal and state authorities can generally prosecute the same conduct under the “dual sovereignty” doctrine, New York law can bar a subsequent state prosecution in certain circumstances when a defendant has already been convicted federally for the same criminal transaction.

Defense lawyer Karen Friedman Agnifilo repeatedly argued that the parallel cases subjected him to two trials for the same alleged conduct. As Mangione was led from a Manhattan courtroom in February, he told reporters, “One plus one is two. Double jeopardy by any common-sense definition.”

His team is likely to argue that the federal stalking conviction and state murder charges arise from the same conduct: the alleged stalking of Thompson, the shooting, and the subsequent fleeing from New York.

The Manhattan District Attorney’s Office responded to Agnifilo’s remarks that it was “prepared to litigate the defense motions” filed immediately after his guilty plea, while remaining “committed to seeking justice for Mr. Thompson and his family.”

Manafort case offers a possible guide

The dispute could echo the case of former Trump campaign chairman Paul Manafort, whose New York fraud charges were dismissed after federal convictions involving substantially overlapping conduct.

A New York judge found the factual overlap between Manafort’s federal and state cases was extensive. An appellate court later upheld that ruling. Notably, current Attorney General Todd Blanche was his attorney at the time.

The comparison is not exact. Mangione’s federal charges are for stalking resulting in death, rather than murder, and prosecutors can argue that the elements and purposes of the federal and state laws differ.

Rahmani said Mangione’s plea could be a strategic gamble. If a state court concludes double jeopardy does not apply, Mangione could still face a murder trial after having admitted under oath to the conduct underlying the federal stalking charges.

A conviction in the federal case does not automatically end the state prosecution. The question will be whether New York courts view both cases as stemming from one criminal transaction or as distinct offenses that may be separately tried.

The guilty plea nevertheless puts the state case in immediate jeopardy and creates a high-stakes legal fight over whether Mangione can be tried for Thompson’s death a second time.