Luigi Mangione arrives in New York for his first appearance in federal court.
AP Photo/Pamela Smith
- Luigi Mangione is in New York to face both state and federal murder charges.
- His new federal indictment alleges he stalked and then killed UnitedHealthcare CEO Brian Thompson.
- Manhattan prosecutors say state charges will "proceed in parallel with any federal case."
Luigi Mangione appeared in federal court Thursday on new federal murder charges that could result in the death penalty or life in prison.