A search team in a helicopter in North Cascades National Park outside of Seattle located the body of John Arum, the eldest son of Top Rank boxing promoter Bob Arum, on Friday.
John Arum's body was discovered at approximately 4:30 p.m. PT at the 7,700-foot level of the north face of Storm King Mountain, which rises 8,815 feet, according to Kerry Olson, public information officer for the park.
Olson said Arum's body was discovered about 300 feet below where his backpack had been found on Thursday.
"We don't know where he was on the mountain when he fell, but we know it was at least a 300-foot fall, but we don't know how far he fell," Olson said.
Arum, an experienced hiker, was 49. The search began on Monday after he failed to return from the hiking trip. He was hiking alone.
According to family members, Arum's goal was to reach the summit of the 100 highest peaks in Washington state. He had hiked more than 80 at the time of his death on the mountain about 85 miles northeast of Seattle.
Olson said Arum's body has not been retrieved.
"It's a very steep location and unstable with loose rock," Olson said. "It's an area where we can't rappel down to it or climb up to it. We are working on a recovery plan and reaching out to see if we can get some help to bring his body back to his family."
Olson said the aerial search began on Wednesday when rainy and cloudy weather cleared.
"His body was in an area that had previously been covered with snow," she said. "[Friday] we had very warm weather and the snow melted and he was visible from an aerial search."
Bob Arum, along with other family members, were notified in person shortly after the discovery, Olson said. She said the family had been staying at a compound where the search was being co-coordinated in the park.
Bob Arum was in Los Angeles on Tuesday to kick off this week's three-city media tour to promote Manny Pacquiao's fight with Antonio Margarito on Nov. 13 at Cowboys Stadium in Arlington, Texas.
Arum left the tour after Tuesday's news conference in Los Angeles and the tour continued to New York and Dallas without him.
Olson said there is an average of one hiking death a year at the park and Arum's was the first of the year.
"We've had six other search and rescues this year where we were able to find and save the others," Olson said.
John Arum, one of Bob Arum's three adult children, was a Seattle environmental attorney.
Bob Arum and his spokesman could not be reached for comment.
Dan Rafael is the boxing writer for ESPN.com; follow him on Twitter @danrafaelespn.