Luigi Mangione's coming state murder trial has been delayed as his defense team makes a bid to dismiss charges there after he admitted in federal court last week to killing UnitedHealthcare CEO Brian Thompson.

The state trial of Mangione, 28 years old, had been scheduled to begin in Manhattan with jury selection on Sept. 8. But that proceeding has been upended after Mangione pleaded guilty last week in a parallel federal case to two stalking charges in connection with Thompson's death in 2024.

During the hearing in federal court, Mangione told the judge: "On the morning of Dec. 4, 2024, I shot Mr. Thompson in Manhattan and he died." Mangione said he had for years endured severe pain from a broken back and navigated the obstacles of the health insurance system.

Mangione faces up to life in prison in the federal case. The judge in that case scheduled his sentencing for Dec. 18.

Shortly after the guilty plea in federal court, lawyers for Mangione argued that the state proceedings couldn't go forward because it would amount to an impermissible second prosecution for the same alleged conduct. The lawyers also accused state and federal prosecutors of coordinating their cases. "The two sovereigns, acting as one, attempted to ensure that Mr. Mangione would be prosecuted twice for the same criminal acts," Mangione's lawyers wrote.

Mangione has pleaded not guilty to the charges in the state case, including second-degree murder and weapons offenses.

In a brief order on Monday, the judge overseeing Mangione's state-court case ordered the district attorney's office to respond to the defense filing by Oct. 9. The next state court date was set for Dec. 10. No new trial date was set.

A spokesman for the Manhattan district attorney's office, which brought the state charges, pointed to a prior statement in which he said that prosecutors had been tirelessly preparing for trial. "While federal sentencing is pending, we are prepared to litigate the defense motions," the spokesman said.

A spokeswoman for Mangione's legal team declined to comment.

The killing of Thompson, 50 years old, came as other top executives at UnitedHealth Group, parent of the largest U.S. health insurer, were getting ready for an investor presentation inside a Hilton hotel in Midtown Manhattan. Prosecutors accused Mangione of meticulously planning the attack, gunning down Thompson on a public sidewalk. Mangione fled, and was later arrested in a McDonald's in Altoona, Pa. after a dayslong manhunt.