Investigators at the Inyo County Sheriff’s Office are trying to identify the hiker and solve the mystery of why he or she never got beyond this spot in “the bowl” as that stretch leading up to the top of Mount Williamson is known.

The mountain is in the Sierra Nevada, more than a four-hour drive from Los Angeles or Las Vegas. The primary rule of getting to the top is not to drop anything while navigating the bowl, said Tinh Le Trung, who works at Elevation, Sierra Adventure Essentials and did the hike two years ago.

“Imagine a bunch of sharp boulders that you have to hop between,” he said. “Lose your phone and you can’t get it back.” And if you twist your ankle on one of the unstable rocks, “you’re done,” he said.

That is p articularly true if you have come up one of the more remote sides of the bowl: “No one will find you,” Mr. Trung added.

People from across the country come for the hike. For Mr. Follin and Mr. Hofer, who are both from San Diego, the attraction was “to do another fourteener,” Mr. Follin, said, using the lingo for a 14,000-foot peak.