Luigi Mangione's lawyers previously told the court their client, who is charged with killing UnitedHealthcare's Brian Thompson, is not a terrorist.

Diary entries written by Luigi Mangione reveal the now 27-year-old’s detailed thinking ahead of the alleged killing of UnitedHealthcare CEO Brian Thompson last year, a new court filing shows.

Manhattan prosecutors said of Luigi Mangione’s handwritten diary entries, “If ever there were an open-and-shut case pointing to defendant’s guilt, this case is that case.”