Mangione crossed state lines. That’s really all Justice needs in a case like this.
ETA: More:
Mangione is charged with one count of using a firearm to commit murder, which carries a maximum penalty of death or life in prison; one count of interstate stalking resulting in death, which carries a maximum penalty of life in prison; one count of stalking through use of interstate facilities resulting in death, which carries a maximum penalty of life in prison; and one count of discharging a firearm that was equipped with a silencer in furtherance of a crime of violence, which carries a maximum penalty of life in prison and a mandatory minimum penalty of 30 years. A federal district court judge will determine any sentencing after considering the U.S. Sentencing Guidelines and other statutory factors.