The judge also threw out evidence in what he said was an unlawful search of Mangione’s backpack as experts weigh in on what the decision means.

A gun and notebook that prosecutors say link Luigi Mangione to the killing of UnitedHealthcare CEO Brian Thompson can be used as evidence at his murder trial. The judge's ruling Monday partially rejects a defense argument that those items were seized illegally, before a search warrant was obtained. It's a major win for prosecutors, enabling them to show the jury a possible murder weapon and evidence they say points to motive. But the judge also ruled that other evidence found during an initial search of Mangione's backpack must be suppressed. Mangione has pleaded not guilty to state and federal charges.

A gun and notebook that prosecutors say link Luigi Mangione to the killing of UnitedHealthcare CEO Brian Thompson can be used as evidence at his murder trial.

A gun and notebook that prosecutors say link Luigi Mangione to the killing of UnitedHealthcare CEO Brian Thompson can be used as evidence at his murder trial.

A gun and notebook that prosecutors say link Luigi Mangione to the killing of UnitedHealthcare CEO Brian Thompson can be used as evidence at his murder trial, a judge ruled Monday, rejecting a defense

A gun and notebook that prosecutors say link Luigi Mangione to the killing of UnitedHealthcare CEO Brian Thompson can be used as evidence at his murder trial.