One of the most troubling mysteries in the history of the Rocky Mountain West began at about 9:45 a.m. on May 29, when three men dressed in camouflage fired 29 shots from assault rifles into Cortez Police Officer Dale Claxton, killing him in the seat of his patrol car.

What followed was one of the largest manhunts in U.S. history, at its peak involving more than 500 officers from dozens of local, state and federal agencies. With a small army of searchers equipped with the latest firepower, technology and training hot on the fugitives’ trail, local residents believed the three men would be caught within days, if not hours.

Now, more than six months later, residents and authorities realize how wrong they were.

Immediately after killing Claxton, the three suspects – Alan "Monte" Pilon, now 31, of Dove Creek;  Jason Wayne McVean, now 27, of Durango;  and Robert Mason, 26, of Durango – began using the survivalist training that authorities believe they had been practicing for years.

During a high-speed chase on County Road G through McElmo Canyon, the suspects fired hundreds of rounds from assault rifles at pursuing sheriff’s deputies, wounding two. The pursuit continued into Hovenweep National Monument, on the Colorado/Utah border, where the three fired at Art Hutchinson, then-superintendent at Hovenweep. Dozens of bullets whipped through the air around Hutchinson and two struck his patrol car, but he was uninjured.

The assailants had not trained for a road battle, but for desert survival. They abandoned their flatbed truck at the rim of Cross Canyon and established a quick ambush site on a hillside overlooking the truck. When no authorities arrived at the truck, the three fled on foot into the sagebrush, juniper and tamarisk trees that cover the canyon walls.

And then they disappeared.

Agencies from dozens of agencies, including the Colorado National Guard, poured into the Four Corners in the days following Claxton’s shooting. More than 500 searchers scoured Cross Canyon between Dove Creek and the Utah border, but days passed with no trace of the three men.

The break the searchers were waiting for came on June 4, when a Utah social worker reported that a man dressed in camouflage had shot at him near Bluff, Utah. Kelly Bradford, a San Juan County, Utah, sheriff’s deputy, was the first man to respond to the scene, and was shot in the shoulder as he stepped from his patrol car. Bradford eventually recovered from his injuries.

Authorities converged on the area near Bluff, and a few hours later discovered Mason’s body in a shallow bunker along the San Juan River. Several explosives were found near Mason, who authorities said appeared to have shot himself in the head with his own pistol.

It has been more than six months since Mason’s body was discovered, and Pilon and McVean remain on the loose. Despite several large searches near Montezuma Creek, Utah, during the summer after a 9-year-old girl reported seeing men resembling Pilon and McVean, the two fugitives continue to frustrate searchers from Colorado, Utah, the Navajo Nation and the FBI.

But although the helicopters are no longer flying over the San Juan River and machine-gun toting police officers no longer walk into the red rock canyons, authorities say the investigation continues.

"I can guarantee you that as long as I’m around, it’ll be an active investigation, and we’ll continue to follow leads and investigate," said Cortez Police Chief Roy Lane. "At some point, we’re going to get a break."

A small group of investigators continue to receive tips at the manhunt command center in Cortez, but so far none of the information has led them to the two suspected cop-killers, despite a $322,000 reward for information leading to Pilon and McVean’s arrests.

Navajo Nation Police Chief Leonard Butler, whose officers had the closest contacts with men resembling Pilon and McVean near Montezuma Creek, said he has plans for future missions in the desert.

"We do have some definite plans to operate in 1999, and we’ll see if those plans bear fruit," Butler said. "My teams are ready and chomping at the bit, and whether it’s a winter operation or we wait until spring, I think we’ll get another crack at them."

San Juan County, Utah, Sheriff Mike Lacy, who in July lit the banks of the San Juan River on fire in order to expose the fugitives, said he thinks the two fugitives will reveal themselves eventually.

"They can only spend so much time out there; even the most-well prepared people can’t last more than a year," Lacy said. "If they are alive, I think we’ll hear from them again."