Luigi Mangione pleaded guilty Friday in New York federal court to stalking that led to the killing of UnitedHealthcare CEO Brian Thompson.

Mangione's plea came weeks before jury selection is scheduled to start for the New York state court trial in which he is charged with murdering Thompson on a midtown Manhattan street in December 2024.

Mangione's defense lawyers are expected to argue that his guilty plea on Friday in U.S. District Court in Manhattan means that he cannot be prosecuted in state court for Thompson's slaying because of New York's double jeopardy law. Double jeopardy bars prosecuting a defendant twice for the same conduct.

The Manhattan District Attorney's Office could argue in response that its case against Mangione is not directly related to the same conduct for which he was charged in federal court.

After a court hearing in February, Mangione said out loud, "One plus one is two."

"Double jeopardy by any common-sense definition," he said.

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