In 1992, Yarbro married Sergei Arsentiev. Together, they climbed many Russian Peaks, including the first ascent of Peak 5800m, which they named Peak Goodwill, as well as Denali via the West Buttress. Arsentiev became the first U.S. woman to ski down Elbrus, and she summitted its east and west peaks. By this time, she had developed an interest in becoming the first U.S. woman to summit Everest without the use of supplemental oxygen.
Everest
Initial attempts
In May 1998, Francys and Sergei Arsentiev arrived at base camp, Mount Everest. On May 17, they ascended from Advance Base Camp to the North Col, and the following day they reached 7700m as 21 other climbers reached the summit of Everest from the North. On May 19, they climbed to 8,200 meters. Sergei reported by radio that they were in good shape and were going to start their summit attempt on May 20 at 1:00am. On May 20, after spending the night at Camp 6, they started their summit attempt but turned around at the First Step when their headlamps failed. On May 21, they again stayed at Camp 6, after ascending only 50–100 meters before turning around.
Summit and aftermath
After these two aborted attempts on the summit, they began their final ascent on May 22. Due to the absence of oxygen supplementation at such high altitude, the two moved slowly and summitted dangerously late in the day. As a result, they were forced to spend yet another night above 8000 meters. During the course of the evening, the two became separated. Sergei made his way down to camp the following morning, only to find that his wife had not yet arrived. Realizing she had to be somewhere dangerously high upon the mountain, he set off to find her, carrying oxygen and medicine. Details of what happened next are uncertain, but the most plausible accounts suggest that on the morning of May 23, Francys Arsentiev was encountered by an Uzbek team who were climbing the final few hundred meters to the summit. She appeared to be half-conscious, affected by oxygen deprivation and frostbite. As she was unable to move on her own, they attended to her with oxygen and carried her down as far as they could, until, depleted of their own oxygen, they became too fatigued to continue the effort. Francys was still alive. As the Uzbek climbers made their way down to camp that evening, they encountered Sergei Arsentiev on his way back up to her. This is the last time he was seen alive.
Death
On the morning of May 24, Briton Ian Woodall, South African Cathy O'Dowd, and several more Uzbeks encountered Francys Arsentiev while on their way to the summit. She was found where she had been left the evening before. Sergei Arsentiev's ice axe and rope were identified nearby, but he was nowhere to be found. Both Woodall and O'Dowd called off their own summit attempts and tried to help Francys for more than an hour, but because of her poor condition, the perilous location, and freezing weather, they were forced to abandon her and descend to camp. She died as they found her, lying on her side, still clipped onto the guide rope. She was aged 40, with one son. Her corpse had the nickname "Sleeping Beauty". The mysterious disappearance of her husband was solved the following year when Jake Norton, a member of the 1999 "Mallory and Irvine" expedition, discovered Sergei's body lower on the mountain face, apparently dead from a fall while attempting to rescue his wife.
"The Tao of Everest"
Woodall initiated and led an expedition in 2007, "The Tao of Everest", with the purpose of returning to the mountain to bury the bodies of Francys Arsentiev and an unidentified climber, both of whom were plainly visible from the nearby climbing route. Francys Arsentiev's body was visible to climbers for nine years, from her death, May 24, 1998, to May 23, 2007. On May 23, 2007, Woodall was able to locate Arsentiev's body, and after a brief ritual, dropped her to a lower location on the face, removing the body from view. "Green Boots" was not seen between 2014 and 2017, and was presumed to have been removed or buried. A body was discovered hanging alongside a tent and other debris on the side of a cliff-face in 2017, which some have speculated to be the transported body of "Green Boots".
