Luigi Mangione has pleaded not guilty to a federal murder charge in the killing of UnitedHealthcare CEO Brian Thompson, as prosecutors formally declared their intent to seek the death penalty against him.

Luigi Mangione pleaded not guilty on Friday to four federal charges that accuse him of stalking and murdering UnitedHealthcare CEO Brian Thompson in December. The 26-year-old defendant made his not-guilty plea in Manhattan federal court,

Luigi Mangione pleaded not guilty in New York federal court to the murder of UnitedHealthcare CEO Brian Thompson. Mangione faces a possible death sentence in the case if he is convicted of murdering Thompson,