A New York judge will allow a gun and writings found in Luigi Mangione's backpack after his 2024 arrest to be presented at his state murder trial, but has ruled that other items are inadmissible.

Judge Gregory Carro ruled on Monday that certain evidence "must be suppressed, including the magazine, cellphone, passport, wallet and computer chip" found with Mangione at a Pennsylvania McDonald's.

Carro said that evidence was recovered as part of an "improper and warrantless search" of the then-26-year-old accused of killing UnitedHealthcare CEO Brian Thompson.

However, prosecutors will be allowed to present items found during a search at a police station, including include a gun and a notebook.

Carro also ruled that some of Mangione's questioning by the officers who initially encountered him at the Pennsylvania fast food restaurant must be excluded from trial. Those include questions about Mangione lying about his name, and asking if he had a fake identification card.

Prosecutors will be able to admit evidence from later questioning, when Mangione was in custody, Carro ruled.

Mangione is accused of shooting and killing Thompson on a Manhattan street in December 2024. He faces state charges including second degree murder, several firearms charges, and stalking. He has pleaded not guilty.

Mangione is also charged in a separate federal case, in which he has also pleaded not guilty.

He was arrested in Altoona, Pennsylvania several days after Thompson's shooting in New York following a nation-wide manhunt.

Mangione's defence team had mounted an aggressive bid to exclude all evidence from the McDonald's stop as well as some of the statements he made to officers. They argued that police improperly searched his bag without a warrant, and did not properly question Mangione.

The court heard several days of arguments over this evidence late last year. Prosecutors argued that the searches and questioning of Mangione were lawful.

Though getting some of the evidence suppressed is a win for Mangoine's legal team, prosecutors will still present two critical pieces of evidence – the alleged murder weapon and writings by Mangione – before a jury.

Mangione appeared in court for the brief hearing wearing a navy-blue suit. He whispered to one of his attorneys while his lead lawyers, Karen Friedman Agnifilo and Marc Agnifilo, conferenced with the judge and prosecutors at the front of the courtroom.

His state trial is expected to start in September.