Luigi Mangione shown videos of UnitedHealthcare CEO killing in court

Luigi Mangione has watched surveillance videos of the killing of UnitedHealthcare CEO Brian Thompson at a court appearance.

Mangione has pleaded not guilty to state and federal murder charges over the killing of Mr Thompson. The state charges carry the possibility of life in prison, while federal prosecutors are seeking the death penalty.

The 27-year-old's lawyers are seeking to bar evidence, including a 9mm handgun and a notebook in which prosecutors say he described his intent to "wack" a health insurance executive, from his New York state trial. Both were allegedly found in a backpack Mangione had with him when he was arrested.

Mr Thompson, 50, was shot dead on 4 December last year as he walked to a New York City hotel for his company's annual investor conference, sparking a five-day manhunt. Mangione was arrested after a McDonald's employee in Pennsylvania alerted authorities to a customer who looked like the suspect in the killing.

Mangione, wearing a white shirt with a red checked pattern under a grey suit, watched without emotion as prosecutors played surveillance videos showing Mr Thompson's killing on a Manhattan pavement, as well as his own arrest, at a court appearance in New York on Monday. The videos, including footage from the McDonald's restaurant in Pennsylvania where he was arrested, kicked off a hearing on Mangione's fight to bar evidence from his trial, including the gun prosecutors say matches the one used in the early-hours attack.

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Eliminating the gun and notebook would be huge wins for Mangione's defence, and a major setback for prosecutors, depriving them of a possible murder weapon and evidence they say points to motive. Mangione also faces seven counts of criminal possession of a weapon, and one count of possessing a false identification.

Judge Gregory Carro dismissed two terrorism counts against Mangione in September. He found that prosecutors had not presented enough evidence that Mangione intended to intimidate health insurance workers or influence government policy.

Trial dates have not been set in either the state or federal cases. Mangione has been held in federal custody in Brooklyn since his arrest..