; (6) the term public agency includes a court system, the National Guard of a State to the extent the personnel of that National Guard are not in Federal service, and the defense forces of a State authorized by section 109 of title 32; and (7) the term public safety officer means an individual serving a public agency in an official capacity, as a law enforcement officer, as a firefighter, as a chaplain, or as a member of a rescue squad or ambulance crew. (b) Offense It shall be unlawful for any person to— (1) kill, or attempt or conspire to kill— (A) a United States judge; (B) a Federal law enforcement officer; or (C) a federally funded public safety officer while that officer is engaged in official duties, or on account of the performance of official duties