sentences:  The planes tend to fly in a tight circle; GPS/radio trackers, cameras, video recorder, and video transmitter installations are documented.It's also presumed to include a IMSI-catcher such as the Stingray phone tracker or the Boeing DRTbox (Dirtbox), which are used by the Marshals' Technical Operations Group.The Marshals Service is based in Arlington, Virginia, and, under the authority of the Attorney General, is headed by a Director, who is assisted by a Deputy Director.