Retired 76-year-old Palo Alto dentist Steve Keller, who went missing 10 days ago in the Wyoming wilderness, has not been found and a search for him has ended.

A spokesperson from the Fremont County Sheriff's Office in Wyoming wasn't available for comment, but Sheriff Ryan Lee told Wyoming news website County 10 there was no sign of Keller and he is presumed to be deceased.

Searchers ended the intensive trek combing the rugged wilderness of the Wind River mountains near Lander, Wyoming on Monday, Sept. 11. Keller disappeared on Sept. 2 during a solo day hike near Steamboat Lake, the sheriff's office said in a prior press release. He reportedly did not have a backpack.

Members of his party searched for him for hours, then sent an SOS call from a satellite communications device.

Wyoming National Guard and Tip Top Search and Rescue helicopters transported search teams into the rugged area. An aerial search also did not find any trace of Keller, according to the press release. Tribal Game and Fish officials also searched for Keller. At one point, bad weather temporarily halted the effort.

Keller worked with the Palo Alto Dental Group starting in 1979 until his retirement. His daughter has not responded to requests for comment.

A niece, Betsy Briggs Miller, said in a Facebook post on Sept. 5 that her uncle is "a skilled outdoorsman who has backpacked this area of the Wind River Range dozens of times. The area he went missing near Steamboat Lake is densely forested and can be disorienting."

The sheriff's office told County 10 that the family was continuing to work with Tribal Fish and Game and might hire a private searcher.