The cause of death was high altitude cerebral edema due to acute high altitude sickness, according to the sheriff's office.
"In laymen's terms, it's when your brain swells," said Sgt. Mark Hilsenberg, who added that their office is still awaiting toxicology results to rule out any other cause of death.
Thomas Bennett, 26, of Oakland, was hiking on the mountain with his friend, 26-year-old Mark Thomas of Berkeley, when the two experienced climbers hit bad weather and were forced to stay the night near the 14,050-foot summit. Thomas made it down by Monday, but Bennett was suffering symptoms of altitude sickness and was unable to descend with him.
Continuing bad weather prevented rescuers from searching for Bennett until last Thursday when they discovered Bennett's body in a snow cave that Thomas had marked.
High altitude cerebral edema causes brain swelling because of fluid that leaks into the brain tissue, said Hilsenberg. Preliminary symptoms include nausea, vomiting, confusion, and finally, coma. If sufferers aren't removed from high elevations right away, said Hilsenberg, the results are "very fatal."
"Every minute, every hour that you can't get your body out of that environment, you deteriorate," he said.
He added that even experienced climbers like Bennett who have been at similar altitudes and never experienced the same symptoms are vulnerable to a quick onset of severe altitude sickness.
"You could be the fittest person in the world," he said. "Human bodies are very fragile."