Hikers on De near Old Tortilla Ranch, where they also found his wallet, backpack, cellular phone, camera, binoculars, sleeping bag, food and water inside a tent, Burnett said. A team of searchers organized by the Maricopa County Sheriff's Office used dogs to cover a 10-mile radius around the tent on Dec. 23, but no trace of him was found in gullies or canyons. Spelunkers crawled through all known caves in the area. Helicopters, airplanes, dogs, volunteers and rescue workers tried again Saturday in a widespread ground and air search, one of many organized during the past several weeks, said sheriff's Deputy Don Roughan. 'There have been no clues found,' Roughan said Saturday. 'It's a pretty desolate area. It looks like you stepped on the moon.' Capen worked a graveyard shift as a bellhop at the Sheraton Denver Downtown Hotel the past 11 years. For 10 years, he spent his free time studying the legend of the Lost Dutchman mine. 'This is beyond obsessed,' Burnett said. 'He has more than 100 books and maps on the legend. This was like research for a Ph.D. This is a classic case of a man's search for treasure.' Capen planned to spend a month searching for the gold mine. He had been there before to search. Thousands of others have searched in the Superstition Mountains looking for the mine during the past 140 years. In the 1840s, the Peralta family mined gold out of the mountains, but Apaches attacked and killed all but one or two family members as they took the gold away. The area became part of the United States in 1848. In the 1870s, Jacob Waltz -- nicknamed 'the Dutchman,' even though he was a native of Germany -- rediscovered the mine with the help of a Peralta descendant, according to legend. Violence has always been linked to the search for the mine. Waltz reportedly shot people who followed him whenever he ran out of money and returned to the mine for more gold. He died without revealing the location of the mine. Movies have recounted the popular tale. Authorities have found skulls of prospectors with bullet holes in the Superstitions. While searching for Capen, Maricopa County sheriff's deputies came across two prospectors armed with handguns in the desert, Burnett said. The deputies took the guns from the men to test them to see whether they had recently been fired, she said. Burnett said her son probably shouldn't have gone there unarmed, but he was a trusting 'gentle giant,' standing 6-feet-4 and weighing well over 200 pounds. After her son went missing, Burnett said, she searched through his apartment for clues about where he may have gone and found maps of the Superstition Mountains and stacks of books on the Lost Dutchman legend. 'My best guess is that he fell and injured himself somewhere and couldn't get up,' Burnett said. Injured, he would have been easy prey for a bear or a mountain lion, she said. 'I tried to give him my bear spray,' Burnett said. 