It said the patrol communication center lost contact with the pilot and called a regional search that involved both military and law enforcement personnel.
Wreckage of the aircraft was spotted about 4 p.m. Benavides, a 13-year patrol officer, was pronounced dead at the scene.
The cause of the crash hasn't been determined and an investigation is under way.
The release said Benavides had just finished working one speed detail and was en route to another on Interstate 8 when he crashed.
Benavides had been assigned to the patrol's border division air operations unit as a pilot.
