Luigi Mangione pleaded guilty Friday to federal stalking charges in the killing of UnitedHealthcare CEO Brian Thompson, an admission that immediately set off a legal fight over whether he can still be tried on separate murder charges in New York state court.

Mangione, 28, entered the plea at a hastily scheduled hearing in Manhattan federal court. “On the morning of Dec. 4, 2024, I shot Mr. Thompson in Manhattan, and he died,” Mangione told the court.

He admitted to emailing UnitedHealthcare ahead of time and posing as a potential investor, using the ruse to confirm the location of the company’s investor conference so he could track Thompson’s whereabouts. Mangione was never a customer of UnitedHealthcare, according to both police and the company.

U.S. Attorney Jamie McDonald told reporters at a post-hearing press conference that it was an open plea and there was no deal with the defense. Now, there’s a question of whether the state can continue its murder trial, scheduled to begin next month. Today’s federal plea does not automatically wipe out the state’s murder trial.

“Mr. Mangione has accepted full responsibility for the death of Brian Thompson,” his lawyer Karen Friedman Agnifilo told reporters outside court, arguing that her client shouldn’t face two prosecutions over a “single tragic event.”