Minutes after Luigi Mangione admitted in federal court that he fatally shot a prominent healthcare executive, his lawyers turned to trying to end the New York state murder case against him, saying he shouldn’t be prosecuted twice for the same crime.

Mangione, 28, pleaded guilty Friday to two federal counts of stalking culminating in the death of UnitedHealth Group Inc executive Brian Thompson, 50. He admitted that he shot and killed Thompson on Dec 4, 2024, and that he knew it was illegal.

Now, his lawyers are seeking to persuade New York Judge Gregory Carro to dismiss the murder case. They say the US Constitution and state law prohibit prosecuting people twice for the same act — a legal concept known as double jeopardy.

“It was a single tragic event, yet he’s being prosecuted twice for the same conduct,” Mangione attorney Karen Friedman Agnifilo told reporters after the guilty plea. “He has been treated differently from every other defendant charged with this offense in New York. However, New York law does not allow this.”

Thompson’s slaying triggered a massive investigation by both federal and New York City authorities, leading to a turf battle and two separate criminal cases against Mangione. US prosecutors indicted Mangione on a murder charge that could have led to the death penalty, but US District Judge Margaret Garnett dismissed that count.

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The upcoming legal battle follows the dramatic decision by Mangione to admit he shot Thompson, exposing himself to a potential life sentence in federal prison. He fled Manhattan after the shooting and was arrested five days later at a McDonald’s in central Pennsylvania after a national manhunt.

He has found support from people who share his rage at the US healthcare system, but US Attorney Jamie McDonald said Friday that anyone who excuses Mangione’s actions is “fundamentally wrong.” He said federal prosecutors will urge Garnett to sentence Mangione to life in prison.

“There can be no celebrity in assassination,” McDonald said at a press conference after the hearing. “Mangione attempted to send a public message through violence. But the message that emerges today is very different.”

Manhattan District Attorney Alvin Bragg, who brought the state charges, said that while he is “encouraged” that the guilty plea has given a measure of “accountability” to the Thompson family, he has no intention of dropping the state case.

“Since December 2024, the Manhattan D.A.’s Office has been tirelessly preparing to pursue a trial conviction in New York State Supreme Court for the alleged cold-blooded murder of Brian Thompson,” a spokesperson for Bragg said in a statement. “The Manhattan D.A.’s Office remains committed to seeking justice for Mr. Thompson and his family.”

In their motion, Mangione’s lawyers said that state and federal prosecutors “charged the identical murder” using “the same firearm” that their client possessed when he was arrested. For that reason, Bragg “is precluded from prosecuting him further.”

Mangione himself has complained about the legal issue, lashing out during a February hearing in the state case.

As court officers led a shackled Mangione out of court at the time, he turned and shouted: “It’s the same trial twice. One plus one is two. Double jeopardy by any common sense definition!”

Judge Carro must decide how to proceed with Mangione’s dismissal request with a trial scheduled to start in his courtroom on Sept 8. However, it’s possible that gets delayed because of all of the publicity in the federal case, which could “absolutely complicate” jury selection in the state case, said Artie McConnell, a former state and federal prosecutor.

“If prospective jurors are reading headlines that the defendant has already admitted guilt to the same or related conduct, that creates obvious challenges for the court and the parties,” said McConnell, who’s now a partner at BakerHostetler.

If the state case goes forward, Mangione faces 25 years to life in prison, which may be in addition to whatever sentence is issued by Garnett. Defense lawyers not involved in the case said that Mangione may have had another reason to plead guilty in US court beyond bolstering his double jeopardy arguments.

“Mangione, like most criminal defendants, would prefer to spend his time in federal custody instead of state custody,” said Neama Rahmani, a former federal prosecutor. “It’s nicer. It’s safer.”

Defense attorney Jeffrey Lichtman said that he doesn’t believe Carro will rule that the two cases constitute double jeopardy. If Carro rejects the request, Mangione’s lawyers would try to go to a New York appeals court – a process that could take months.

“It may or may not work, and they figure it’s worth a shot,” Lichtman said.