Bennett is believed to be in a snow cave near the summit, above 14,000 feet. His companion, Berkeley's Mark Thomas, was rescued Monday.
Thomas' father lives in Salt Lake City.
"His climbing partner unfortunately appeared to have cerebral edema and died up on the summit," Jay Thomas said. "Mark tried to bring the body down but deemed it too unsafe to do that."
Berkeley's Richard DeYoung has climbed Shasta several times, including the northern path taken by Bennett and Thomas.
"They have more glaciers on the north side, the ice has cracks in it and has crevasses and because the crevasses can be bridged, you can walk over one, slip through the snow and be crashing down in a canyon of ice that can hurt you," DeYoung said.
Climber Leo Burk once attempted the same route as Bennett and Thomas.
"It's steeper than the south side," he said. "There was too much snow, so you couldn't see where the bridges were, the snow bridges. We decided it was too dangerous and we came back down."
Thomas told rescuers he left Bennett in a snow cave with water and granola bars. According to Thomas, Bennett became confused and disoriented and then unresponsive.
"You would suspect there's some disorder of the brain function," Dr. Glen Petersen said.
Petersen says many factors can come into play at that altitude; low oxygen can lead to altitude sickness and cold weather can lead to hypothermia.
"There's a combination of factors that could affect the brain, and the other thing about it is, it's a variable thing, it doesn't affect everyone equally," he said. "This could explain why one of the individuals was intact and the other was confused."
Contrary to earlier reports, authorities confirmed Tuesday that Bennett and Thomas had the proper climbing permits to be on the mountain and had checked weather reports before beginning their climb.
Due to bad weather, rescuers do not believe they will be able to resume their efforts until Thursday.
Bennett moved to Oakland from British Columbia about one year ago and had recently become engaged to be married.
