A century ago, Pinkerton detectives and bounty hunters rode on horseback through the red-rock canyons and mesas of southeast Utah, trying to track down two outlaws, Butch Cassidy and the Sundance Kid.

This summer, as many as 500 law officers have been searching the same mesas and canyons for two men suspected of killing a police officer and wounding three sheriffs. Searchers have used infrared cameras, night-vision scopes, motion detectors, radios with encrypted transmissions, smoke bombs, armored personnel carriers, four-wheel-drive vehicles, airplanes and helicopters.While today's wanted posters offering a $327,000 bounty are broadcast on television, the searchers are finding themselves just as empty-handed as the Pinkertons in territorial days, when posters for the two outlaws and their Hole in the Wall gang were circulated by hand.

On May 29, the fugitives vanished into this vast no man's land known as the Four Corners, where the boundaries of Colorado, Utah, Arizona and New Mexico meet. Two months later, the authorities do not know if the pair are dead, in hiding or enjoying life in Mexico.

"If you know the territory, you can survive," said Duane Smith, a Western history professor at Fort Lewis College in Durango, Colo. "Butch Cassidy, and now these guys, knew how to keep one step ahead."

The manhunt centers on San Juan County, Utah, a jurisdiction that includes part of the Navajo reservation, as well as 5,600 square miles of uninhabited public land, an area larger than Connecticut. A mythic outlaw landscape to generations of Americans, this country of canyons, pinyons and Indian ruins served as a Western backdrop for Zane Grey's 1912 novel "Riders of the Purple Sage" and for the 1990 film "Thelma and Louise."

"I am not making any statements to glamorize these two," Leonard Butler, chief of police for the Navajo Nation, said of the wanted men, Alan Pilon, 30, and Jason McVean, 26. "They are cop killers. They have wounded deputies."

The police say that around noon on May 28, Pilon, of Dove Creek, Colo., and McVean, of Durango, Colo., walked into an oil-service company in Ignacio, Colo., about 100 miles east of here, and stole an empty water truck.

The next morning, Dale Claxton, a Cortez, Colo., police officer, spotted the missing truck about 50 miles west of Ignacio, by which time a friend of the two men, Robert Mason of Durango, had joined them, according to police affidavits. As the truck stopped at a bridge, Claxton pulled up behind it. As he sat in his police car, with his seat belt still fastened, a passenger jumped out of the truck and fired 29 bullets into the car, killing Claxton. Fifteen minutes later, the affidavits say, the men in the water truck stole a flatbed truck from a construction worker and posted one man with an automatic rifle in the back.

Jason Bishop, a Montezuma County deputy sheriff, remembers looking in his rear-view mirror to see the truck roaring up behind him. A man in camouflage appeared over the cab and sprayed his police car with automatic weapon fire, Bishop said. Shot in the head, the officer lost consciousness and his car veered off the road and rammed a shed.

In the next few minutes, the affidavits say, passengers in the stolen truck fired as many as 500 bullets at several police cars that had joined the chase.

Driving farther west into Utah, the fugitives encountered Art Hutchinson, superintendent of Hovenweep National Monument, trying to block access to the park with his car. The fugitives riddled his car with bullets, swerved around it and entered the park. Hutchinson, who took cover in a ditch, was not hit. After driving across the park, the fugitives parked the truck at the head of a canyon and disappeared.

A week later, the authorities say Mason apparently fired on a Utah state welfare worker along the San Juan River near here and then on a San Juan County sheriff's deputy, wounding him in the shoulder and the chest. Minutes later, searchers found Mason's body. According to an autopsy, Mason had placed a pistol in his mouth and pulled the trigger.

Officers have interviewed hundreds of people to prepare profiles of the two remaining fugitives. Both are described as men who mix an intimate knowledge of the desert region with a hatred of the government and a conviction that society will break down with the end of the millennium.