FRESNO, Calif. » Investigators have ruled the deaths of two wingsuit fliers who died earlier this year in California’s Yosemite National Park as accidental, but the reasons why they died remain a mystery.

The Associated Press obtained investigation reports detailing the fatal crash by world-famous wingsuit flyer Dean Potter and fellow adventurer Graham Hunt. On May 16, the pair leaped from Taft Point, 3,500-feet above Yosemite Valley, attempting to clear a V-shaped notch in a ridgeline.

Investigators say that Potter had strapped his iPhone to back of his head and pressed record to capture Hunt soaring behind him.

They say it recorded 22-seconds of flight before Potter and Hunt crashed into the ridge, killing both.

Investigators say several possible factors may have led to the crash, including indecision, distraction, miscalculation or air turbulence.