Two world-class alpinists who apparently pioneered a challenging new route up the Mendenhall Towers near Juneau are presumed dead, Alaska State Troopers said.

George "Ryan" Johnson, a 34-year-old Juneau resident, and 25-year-old Marc-Andre Leclerc of Squamish, British Columbia, got to the top of their climb Monday. The route they chose up the 6,910-foot main tower via the north face appears to have never before been climbed, according to a story in Outside Magazine online.

The towers jut from the Juneau Icefield about 12 miles north of the city. The pair never returned to the pile of gear they cached for the ski out across the ice field and trip down the West Mendenhall Glacier Trail back to Juneau, troopers said.

Bad weather complicated search efforts for days, but members of Juneau Mountain Rescue on Tuesday were finally able to get a good look at the north face of the Towers from a chartered Coastal helicopter.

They glimpsed an anchor rope at the top of an ice chute on the fourth tower and two climbing ropes in a crevasse midway down the tower, according to troopers spokeswoman Megan Peters. The ropes match the description of Johnson and Leclerc's gear.

"Everything tells us they are down in that crevasse and they are presumed deceased," Peters said.

It's not clear whether Johnson and Leclerc fell into the crevasse or an avalanche carried them into it, she said. "We do know they ascended, took pictures at the top. … We know they hiked a ridge over to the ice chute near the fourth tower."

It will likely be summer before a team can attempt to recover their bodies given the avalanche danger in the area, she said.

Leclerc had posted what he called a "rare live update'' at the top of the tower — a stunning photo of snowy peaks all the way to Mount Fairweather under bright blue skies.

At the top, Leclerc reached out to his father and a close friend, according to John Irvine, who handles global community marketing for Leclerc's sponsor, North Vancouver-based Arc'teryx.

"He took an Instagram photo. Then he and Ryan started a descent," Irvine said Wednesday.

The men weren't heard from again.

Their friends and families notified authorities the evening of March 7 after Leclerc and Johnson failed to return from the climb. But bad weather grounded the search for days, with scant windows providing only brief opportunities to look for the duo as their families and the international climbing community waited for word.

Neither of the men carried a satellite phone or emergency beacon, troopers said.

Leclerc's father, Serge Leclerc, posted an update on his public Facebook page Tuesday evening: "Sadly we have lost 2 really great climber(s) and I lost a son I am very proud of."

Leclerc's family established a GoFundMe page for relatives and his partner, Brette. An unidentified mentor quoted on the page praised Leclerc's unparalleled energy and enthusiasm and his "amazing" skills but said what made him special was "his ability to 'see' possibilities where no else could even begin to imagine."

Nearly 800 people had donated as of Wednesday, raising more than $38,500 in four days.

Johnson's relatives also set up a GoFundMe page originally intended to pay for search efforts that has now become an account to help family and friends "with closure and costs" related to his death. The fund is also intended to help Johnson's 2 1/2-year-old son, Milo, "who will be missing his father and father's support intensely."

By Wednesday, the site had raised more than $37,000 from 500 people in two days.

The men's names will remain listed on a missing-persons clearinghouse until their bodies are found.

Leclerc was a rising star in the alpine climbing community and already considered one of the top alpinists of his generation. His solo climbing — done without the support of a second person — included spectacular feats among the jagged peaks of South America's Patagonia.

A report by Rock and Ice called Leclerc's 2015 solo climb of a route on 10,200-foot Cerro Torre "by far the hardest route" ever solo-climbed there.

Irvine called him a prodigy who made winter ascents his medium but also took the time to help with climbing clinics when he was home.

The same Rock and Ice article said Johnson "made waves" in the Mendenhall Towers in 2011 when he free-climbed without ropes a line on the South Buttress of the main tower. He also established a demanding line on the west tower in 2008.

Johnson co-owns a gym in Juneau called Tongass Fitness. He was a national-level swimmer in his younger years and completed difficult climbs in the U.S., Canada, Kyrgyzstan and Nepal, according to the gym website.

People waiting for word on Leclerc and Johnson's fate for a week remained "very, very hopeful" to the end, Irvine said.

"Both Marc-Andre and Ryan were very skilled climbers. They were very experienced climbers. They'd been in winter storm situations before," he said. "People were genuinely hopeful they were holed up on a ledge, in a snow cave somewhere, and just holding their ground."