Lawyers for Luigi Mangione on Friday continued to push for the dismissal of his state court murder and weapons case, arguing that his guilty plea to federal stalking charges two months ago bars a separate trial. Mangione, the admitted killer of UnitedHealthcare CEO Brian Thompson, pleaded guilty in Manhattan federal court in August. The plea set off a protracted battle over the future of the separate state court prosecution for second-degree murder and weapons possession. His state trial, slated to start Sept. 18, was postponed indefinitely so the court could take up whether double jeopardy applies. A decision on the dismissal motion is expected Dec. 10.

Manhattan District Attorney Alvin Bragg’s office maintains the state case can legally proceed because its charges differ substantially from those in the federal court case, which centered on stalking and crossing state lines and cyberstalking through use of interstate facilities, each resulting in death. The state indictment is a classic murder case, prosecutors argued, and murder is generally not defined by federal statutes.

Mangione’s team countered Friday that the charges in the two cases are materially the same. They told New York Supreme Court Justice Gregory Carro that the federal offenses Mangione pleaded guilty to, interstate stalking resulting in death, involves overlapping legal elements. “Here, Mangione was charged by the federal grand jury with possession of the same firearm at the same time and at the same location as the People are charging here,” Mangione’s attorneys Karen Friedman Agnifilo, Marc Agnifilo and Jacob Kaplan argued in a letter to the court. “There is and was no other gun.”

Mangione faces a potential life sentence when he returns to federal court on Dec. 18. If the state case goes forward, he faces a maximum of 25 years to life in prison.

State prosecutors must overcome New York state double jeopardy law, which requires distinct “evils” between the two cases for the state matter to proceed, legal experts told NBC News. Mangione’s lawyers say the harms addressed in the state and federal cases are one and the same. “There is no basis to find such a difference, much less a sufficiently great difference as to fit within the narrow statutory exception,” they wrote in their most recent submission.

Earlier this month, Bragg’s office pointed to a double jeopardy exception that could give it a path forward if Carro finds that there were unique “elements” charged in the state case. Lead prosecutor Joel Seidemann argued in a filing that earlier litigation in the federal proceeding shows the state charges are significantly different. U.S. District Judge Margaret Garnett determined that the stalking could not be considered violent under the law, a ruling that led to the dismissal of two counts that would have made Mangione eligible for the death penalty.

The Justice Department had announced its intention to seek capital punishment before Garnett’s ruling. Mangione admitted to using a 3D-printed firearm to shoot Thompson outside of the midtown Hilton early on Dec. 4, 2024, as the executive walked from his nearby hotel to his company’s investor conference. The gunman ambushed Thompson, a Minnesota father of two, firing several times before fleeing and setting off an interstate manhunt. He was arrested five days later in Altoona, Pennsylvania, after patrons recognized him at a McDonald’s from photos circulated by the NYPD.

The Ivy League-educated Maryland native, who comes from a prominent family, said in federal court that he was motivated by a personal grievance with the health insurance industry. Investigators have said he was never a UnitedHealthcare policyholder.

His attorneys have argued that case’s notoriety led to overprosecution, with state and federal officials seeking credit by pursuing separate cases for the same event.