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 ...