Luigi Mangione’s state murder trial has been postponed following his guilty plea to federal charges last Friday in the killing of United Healthcare CEO Brian Thompson.

His defence team is now fighting to have the state case dismissed on the grounds it would constitute double jeopardy – a constitutional protection that bars prosecuting a person twice for the same crime.

The Manhattan District Attorney’s office must now respond to Mangione’s bid to throw out the case by 9 October, Judge Gregory Carro ordered on Monday.

Jury selection for the state murder trial was initially set to begin on 8 September. The next court date is scheduled for 10 December.

Mangione faced two separate prosecutions over Thompson’s death: a federal case brought by the US government, and a New York state case brought by the Manhattan District Attorney.

Last week, Mangione pleaded guilty to two criminal stalking charges in the federal case, admitting he killed Thompson.

“On the morning of December 4, 2024, I shot Mr Thompson in Manhattan and he died,” Mangione told a courtroom packed with attorneys, prosecutors, press, observers, and Thompson’s family.

A few moments later, asked by a federal judge to state his plea, Mangione declared, “Guilty.”

Mangione’s lawyers then immediately filed to dismiss his state charges, arguing that New York law prohibits prosecuting him twice for the same conduct.

Judge Carro has set an October deadline for both the prosecution and defence to file motions on the matter before deciding the fate of the state case.

Mangione faces eight state charges, including second degree murder, for all of which he has pleaded not guilty.

The Manhattan District Attorneys office said Friday it had been “tirelessly preparing to pursue a trial conviction” and was “prepared to litigate the defence motions”.

Mangione’s sentencing in his federal case will occur on 18 December. The charges carry a maximum penalty of life in prison.