A Manhattan judge ruled Monday that prosecutors can use a gun and notebook found in Luigi Mangione's backpack as evidence in his state murder trial for the killing of UnitedHealthcare CEO Brian Thompson, while suppressing other items seized during his arrest.

Judge Gregory Carro allowed the 3D-printed pistol, which prosecutors say matches the weapon used to kill Thompson, and a notebook described by prosecutors as a "manifesto" that allegedly describes wanting to "whack" a health insurance executive. However, the judge ruled that evidence found during the initial search of Mangione's backpack at a McDonald's restaurant in Altoona, Pennsylvania, must be suppressed, including a gun magazine, cellphone, passport, wallet and computer chip.

"I find that the search of backpack at the McDonald's was an improper warrantless search," Carro said in his ruling. The judge distinguished between the initial search at the restaurant and a subsequent inventory search conducted at the police station, which he deemed permissible under standard police protocols.

Mangione, 28, was arrested on December 9, 2024, five days after Thompson was shot and killed outside a Manhattan hotel. Police found him eating breakfast at the Pennsylvania McDonald's, approximately 230 miles west of Manhattan. During the arrest, Mangione initially provided a fake name, Mark Rosario, which gave police grounds to detain him.

The ruling represents a partial victory for both sides. Prosecutors retain access to what they consider key evidence linking Mangione to the December 4 shooting, including the alleged murder weapon and writings that could establish motive. Defense attorneys successfully challenged the initial search, arguing it violated constitutional protections against unreasonable searches.

Mangione has pleaded not guilty in both state and federal cases. His state murder trial is scheduled to begin September 8, with jury selection for the federal case set for October 13. He faces the possibility of life in prison if convicted in either case.