Bubbette,
It is not unusual to see cargo aircraft belonging either to DHL/Federal Express/UPS/Airborne Express and other such companies parked in exactly the same location at many airports around the country. They fly mainly at night. Depending on how the company rotates its fleet, the give away might be the airplane's tail number, which will be different from day to day or week to week. Failing that, it may be an airplane which has been impounded by the authorities.