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.

Prosecutors told the judge this week they intend to seek the death penalty in shooting death of UnitedHealthcare executive Brian Thompson

Luigi Mangione, who is accused of shooting UnitedHealthcare CEO Brian Thompson dead in New York City, has entered a plea of not guilty as prosecutors say they are seeking the death penalty