An autopsy Tuesday did not lead to any determination as to what caused the death of a Glens Falls man who died while hiking Sunday on Dix Mountain in the Adirondack High Peaks.

Medical staff who performed an autopsy Tuesday at Champlain Valley Physicians Hospital in Plattsburgh could not draw any conclusions as to what caused Andrew J. Nichols, 21, to die Sunday night during a long hike.

State Trooper Jennifer Fleishman said autopsy results were still pending, with histology and toxicology analysis to be performed.

She said what caused the medical problem that led to Nichols’ death was a “conundrum,” as he was an experienced hiker and skier who had extensive gear for the hike he and a partner took on in the town of Keene, starting early Sunday.

The friend who was with Nichols did not suffer any medical issues and did all he could to try to help Nichols get off the mountain when he began having problems.

“He was very fit and an experienced hiker,” Fleishman said. “From what we were told, it just happened so quick.”

Fleishman said Nichols and the friend, whose name wasn’t released, set out to hike the Dix Mountain Range in the High Peaks Wilderness around 6 a.m. Sunday. Dix Mountain is the sixth highest peak in New York state at nearly 4,900 feet, and all of the approaches are difficult hikes.

The mountains had extensive amounts of new snow as of early Sunday and the men, hiking in snowshoes, were breaking trail with snowshoes in about 3 feet of new snow, Fleishman said.

The friend told police that Nichols reported getting too warm and took off layers of clothes, but hypothermia seemed to set in quickly and Nichols was slowing down significantly as they tried to make their way out of the woods.

At some point, they became “disoriented,” which didn’t help their efforts to get out of the woods.

“They walked out as far as they could, but he was failing and became unconscious,” she said. “He (the friend) tried CPR for quite a while.”

When forest rangers made it to the men’s location, Nichols was not breathing and did not have a pulse. His body was removed from the woods Monday morning.

Police did not say how far from the trailhead the men were at that point.

Nichols was a 2016 Glens Falls High graduate and avid hiker and skier, who had hiked more than 20 of the High Peaks.

He also had attended SUNY Adirondack in Queensbury, and worked at both Gore Mountain and West Mountain ski centers.

Remembrances of him and an outpouring of support for his family continued on social media late Monday and Tuesday.

“You were one of the kindest souls and one of the easiest going people I’ve ever had the pleasure knowing,” wrote Breana Garcia.

“You were such a great person and meant nothing but good to everyone,” wrote friend Josh Charles. “I remember like it was just yesterday when we reached the summit of your first high peak and you kept going ever since.”