Ranger Jason Caffey was on routine patrol, miles from anywhere, when he saw it: A rock shelter that archeologists have been excavating for a decade had been looted, scooped out in the middle with thousands of stone artifacts and bone fragments cast aside.
But since Caffey's discovery in June in rugged, remote northern Wyoming, no arrests have been made and leads have been sparse. The incident points out the difficulty that a limited number of federal officials in the field face in protecting remote archeological sites containing valuable artifacts.
Researchers are hoping to salvage what they can at BA Cave rock shelter, a shallow hole on a mountain they had believed could help provide clues about the environment and human dwellers in the region thousands of years ago.
"It's going to be a significant impact on ongoing research," said Mike Bies, an archeologist in the BLM's Worland field office. "They moved as much dirt in one event as we moved in 10 years."
Strangely, small-scale looting in the early 1990s provided an impetus for work at the site and a research agreement between the BLM and University of Wyoming. Artifacts suggest the site was occupied about 7,000 years ago, and perhaps earlier, Bies said. That is one of the things researchers have sought to establish.
Deliberate excavations so far have yielded a wealth of artifacts and environmental data about 3,700 years old; details have been carefully mapped and recorded, said Marcel Kornfeld, an associate professor of anthropology at the University of Wyoming.
Archeologists, often working in soft dirt with paintbrushes or bamboo picks, have recovered items -- such as tools, bone and stone artifacts, and plant remains and pollen -- that officials say help provide clues to climate and environment. Layers of cultural evidence have also been revealed, officials said.
The work originally began at the edges of the previous looting. Archeologists hadn't touched the portion gouged out in the latest incident, which Bies said claimed half of the shelter's interior and cut through deposits at least 3,000 years old.
Looters left behind thousands of pieces, many seemingly sorted, Bies said, including bone pieces, stone artifacts and parts of projectile points.
"It looks like they sorted the bone and chips, like they knew they wanted something better," he said.
Just what the looters wanted or actually got isn't clear and, officials concede, may never be. The BLM has calculated damages at almost $7 million.
David Tarler, an attorney and consultant on protection issues, said looting on federal lands is a problem that often goes unnoticed. "Looting isn't like robbing a bank," he said.
The BLM has six law enforcement rangers who oversee roughly 18 million acres in Wyoming, spokeswoman Cindy Wertz said. The agency relies on employees and the public to report problems.
"We really rely on education, getting the word out that things they find on public land are protected," Wertz said.
But, she acknowledged, publicizing certain areas -- such as the Black Mountain Archeological District that includes the BA Cave and similar formations and is listed on the National Register of Historic Places -- can be a double-edge sword.
Tim Nowak, archeologist in the BLM's state office, said caves and rock shelters are popular targets for vandals and looters, despite their often remote or dangerous locations.
"The type of people that go after those types of resources are really interested in getting up there," he said. "They know that's where the cultural resources are untouched. It's not something the everyday vandal would do."
The rockshelter, although remote, is accessible by horse, four-wheeler or pickup, officials said, but reaching it can be harrowing this time of year.
Even if an artifact were for sale at an online auction or a special show, it would be very difficult -- if not impossible -- to know for sure where it came from, he said. Complicating matters further in this case is that officials don't even know what was taken.
The BLM is offering a $20,000 reward for information leading to the looters' arrest and conviction.