FARGO, N.D. -- A North Dakota State University professor climbing Mount McKinley the day four Japanese climbers were killed said he worries he might have missed an opportunity to recognize an emergency and quickly call in a rescue party.

Berlin Nelson told The Forum newspaper he encountered a Japanese man on the mountain in Alaska on June 13, the same day five Japanese climbers were likely swept into a crevasse by the avalanche. Four died. Hitoshi Ogi, 69, climbed 60 feet out of the crevasse and eventually reached a camp.

Nelson said the tracks of the Japanese man he encountered on the mountain that day seemed to trace back to the avalanche area, but the man indicated in broken English he was resting but unharmed.

Nelson and his climbing companions did not learn until days later of the climbing deaths.

"It bothers me that we either didn't perceive that there was a problem or he just couldn't communicate with us," said Nelson, a McKinley veteran. "We had a satellite phone with us. They would've sent a rescue team immediately."

The avalanche came to rest approximately 100 yards from Nelson's tent at a camp about 11,000 feet up the mountain. It wiped out much of a nearby trail, but Nelson did not think much of it at the time and began his descent later that morning. The identity of the climber he encountered has not been confirmed, but both Nelson and McKinley park rangers believe him to be Ogi.

"I wish I could talk to him again to find out why he didn't say anything," Nelson said.

Park spokeswoman Maureen McLaughlin said shock, disorientation, exhaustion and the language barrier all could have hampered Ogi's ability to communicate.

"There are physical impacts and emotional ones as well," she said. "In circumstances like these, it's very rare that someone would survive."