Last week, Outside reported on the Ukrainian Everest expedition that left $50,000 worth of cryptocurrency on the summit of Everest. On May 14, Taras Pozdnii, Dmitry Semerenko, and Roman Gorodetskiy summited the mountain and buried the goods as part of a publicity stunt for Ireland-based social media startup ASKfm.io. A video shows the climbers on the summit as snow falls.

But we missed one very crucial piece of information: as the three climbers and their two Sherpa descended, 45-year-old Lam Babu Sherpa disappeared.

Soon after the summit, the weather began to deteriorate. By their account, the three Ukrainians left Lam Babu and Mingma Sherpa behind as they raced back to the South Col, at 25,938 feet. Along the way they stopped to help Chinese climber Saber Liu, who was alone and out of oxygen. Together the Ukrainians and Liu reached the South Col. Pozdnii and Gorodetskiy spent the night there with Liu, while Semerenko descended to Camp 2. “The death zone starts at 8,300-meters,” Semerenko told me. “It's every man for himself zone.”

In a written statement to Outside, Semerenko criticized the support they received from Lam Babu and Mingma Sherpa, who both work for Seven Summits Treks, a low-cost Nepal-based guide company. “We could tell by the look [of] them that they were inexperienced, and had to clarify if they [had] ever been to Everest before,” he wrote to me. “They barely understood English and basically were porter Sherpas.” He said they carried extra oxygen bottles and often lagged behind the three climbers.

Lam Babu was no rookie in the Himalaya, however. He summited Everest three times and has ascents of Cho Oyu, Manaslu, and Annapurna, all 8000 meter peaks.

Mingma Sherpa made it down the mountain, but it’s still unclear precisely what happened to Lam Babu. Gyanendra Shrestha, the Ministry of Culture, Tourism, and Civil Aviation's representative at Base Camp, said Lam Babu went missing and the rescue team stationed at Camp 2 was unaware of the incident as it unfolded. At this point, Lam Babu is presumed dead. Mingma Sherpa did not immediately respond to a request for comment. I'll update this story if he does.