Longtime Rim country resident and businessman Ray Hill remains in critical condition in the intensive care unit of Scottsdale Healthcare hospital.
Hill suffered severe head trauma when his vehicle went off a 60-foot cliff on Four Peaks Road early Monday morning and he was ejected.
The Maricopa County Sheriff's Office is investigating the accident.
"They are looking into the possibility of driver impairment," said Sgt. Paul Chagolla, MCSO public information officer. Officials declined to elaborate on what evidence might lead to that conclusion.