One theory: Mangione wants to spend the rest of his life in a Federal prison, not a state prison. Federal prisons are much nicer. If the Federal judge sentences

One theory: Mangione wants to spend the rest of his life in a Federal prison, not a state prison. Federal prisons are much nicer. If the Federal judge sentences him to life, and the state charges get dropped (double jeopardy) -- he goes to Federal prison.