A cowboy clomping through rugged Cross Canyon east of Hovenweep National Monument on Tuesday came upon bones and a camouflage backpack. A closer look revealed the pack was laden with pipe bombs.

Later, authorities inspecting the site turned up an AK-47 assault rifle and 500 rounds of ammunition along with survival gear.

Authorities are all but certain the remains are those of Jason Wayne McVean, the last of the "Four Corners Fugitives."

"We're 99 percent sure it's him," San Juan County Sheriff Mike Lacy said Wednesday.

The 26-year-old Durango man had been missing for nine years - since May 29, 1998, when he - along with Robert Matthew Mason, 26, of Durango, and Alan "Monte" Pilon, 30, of Dove Creek, Colo. - killed a Cortez, Colo., policeman with automatic weapons and wounded two Montezuma County, Colo., deputies before disappearing across the state line into the vast desert of Utah.

Mason was found dead a week after the Cortez shootings, and Pilon's skeleton turned up 17 months later.

The latest remains have been delivered to the FBI for positive identification. But it may be impossible to determine the cause of death, Lacy said.

"The skull was completely in pieces and many of the body parts were missing. They'd been dragged off by coyotes."

But forensic specialists should be able to make an ID through dental records, the sheriff said.

A $170,000 reward will be paid to the cowboy, who asked authorities not to identify him.

Among the remains, investigators found Pilon's business card and a wristwatch that had stopped on the 30th at 6:35. Lacy believes McVean died at that time on May 30, the day after the Cortez shoot-up. It's unclear whether it was in the morning or evening.

By contrast, Mason was found with a gunshot wound through his mouth and blunt-force trauma to his head almost 50 miles away, near Bluff. Investigators called it a suicide. But the Utah medical examiner's office refused to label it as self-inflicted.

Pilon's skeleton was found by deer hunters in October 1999 not far from where the trio ditched the truck. He had suffered a broken ankle and had a gunshot wound through the top of his skull. San Juan County investigators believed it, too, was a suicide. But again the coroner refused to rule it as such.

The remains believed to be those of McVean were found two miles from Pilon's.

For years, some, including Mason's mother, believed McVean may have made a clean getaway. The conjecture was the threesome had stashed a boat on the San Juan River near Bluff and that McVean had slipped down river and eventually made it to Mexico.

But Lacy, who always maintained McVean had died in the desert, said that lore can be laid to rest. It vindicates Utah and Colorado law enforcement, he said.

"There is no more legend. It's over with."

Maybe. But McVean's presumed demise means no one ever will know why the three, decked out in camouflage and armed with automatic weapons and pipe bombs, stole a 2 1/2 -ton water truck in Ignacio, Colo. Why they were driving it around a residential area the next morning in Cortez. Or why they shot and killed Officer Dale Claxton after he pulled up behind them in his cruiser.

"There are a lot of theories," Cortez Police Chief Roy Lane recalled Wednesday. "But nobody knows what they were up to."

Some surmised the trio planned to use the water truck as a "war wagon" to rob the nearby Southern Ute casino. Others believed the self-styled survivalists were taking the truck to a desert hide-out where they would await the collapse of society.

Whatever the reason, the bloody shooting spree remains fresh in the minds of Cortez residents, the police chief said.

"It had a terrible impact on the community and the Police Department - the bloodthirsty way in which it was carried out," Lane said. "But this provides closure for everybody, I hope."

In 2003, Mason's mother, Ann Mason, said she was unaware of her son's plans or that he was capable of such violence. She maintained that neither her son nor Pilon committed suicide.

She has since moved from Durango and could not be reached.

McVean's father, Jim McVean of Durango, refused comment Wednesday.

After killing Claxton, the three fugitives ditched the water truck at a Cortez construction site, where they stole a flatbed truck. Racing out of town, they shot two deputies. Both men were hospitalized. Later that morning, a park ranger at Hovenweep reported being shot at by men in army gear driving a flatbed.

Law enforcement officials from across the West descended on San Juan County. Some 500 officers scoured the vast area known for its numerous canyons and draws. They found the truck in a dry streambed not far from the monument. But authorities had no luck sighting the fugitives.

Finally, on June 4, a state social worker called the sheriff's office just before noon to say he had been shot at outside Bluff near a swinging bridge over the San Juan River.

At 12:50 p.m., San Juan County Deputy Kelly Bradford drove to the scene and was shot and seriously wounded on a ledge overlooking the bridge. But by the time a Pueblo County, Colo., SWAT team closed in on Mason, at 5:48 p.m., he was dead.

Now what is left are unanswered questions, said Sheriff Jerry Martin of neighboring Dolores County, Colo. Martin helped in the manhunt nine years ago. He, too, believes Pilon and Mason committed suicide and that McVean also may have killed himself.

"It gives me a sigh of relief and a little satisfaction," he said Wednesday afternoon. "But I, for one, would have liked to sit in on an interview with [McVean]. I think they were up to something big, but now we'll never know."

csmart@sltrib.com---

* Tribune correspondent LISA J. CHURCH contributed to this story.