Luigi Mangione pleaded not guilty to federal charges including murder and stalking Friday at his arraignment in the killing of UnitedHealthcare CEO Brian Thompson, crimes for which he could get the death penalty if convicted.

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, the Maryland man accused of hunting down and killing a UnitedHealthcare CEO over what prosecutors said was "hostility toward the health insurance industry," pleaded not guilty at his Manhattan federal court arraignment on Friday to what could be death penalty charges.