Matthew Thomas, supervisor of the traffic enforcement unit at the sheriff's office of Pinal County, which contains the highest-speed stretch of Route 79.
Border Patrol officers originally spotted the white Ford Excursion around 4:30 a.m. off the side of Interstate 8 in western Pinal County, about 60 miles south of Phoenix.
The latest incident occurred around 12:30 p.m. local time on Thursday in a rugged part of the U.S. Special Operations Command facility at Pinal Airpark, military officials said on Friday.