CORTEZ – Three alleged cop-killers, at least one of whom an official said was from La Plata County, eluded an expanding manhunt for the fourth day Monday.

Authorities expressed frustration that the fugitives had not been found a day after new evidence led them to believe they were closing in.

Instead, search crews backtracked over ground already covered and expanded their search of the dry canyons northwest of Cortez.

Montezuma County Sheriff Sherman Kennell and other officials said the fact that the fugitives have done so well evading authorities indicates the three were familiar with the Hovenweep National Monument area and had some survivalist training.

Kennell feared when they are caught, the fugitives will want to go out in a blaze of glory.

"My guess is it will be a violent situation," Kennell said. "I don’t think it will end peacefully."

Cortez Police Chief Roy Lane said investigators had determined the names and addresses of the three early Monday morning, but he would not release the names. He said they were only the focus of the investigation, and were not yet considered suspects.

But a Montezuma County sheriff’s deputy, when asked by the Durango Herald whether the fugitives were from the Durango area, said, "From what I understand, they are from your neck of the woods." He spoke on condition of anonymity.

Cortez police Officer Dale Claxton, 45, was fatally shot while in the front seat of his patrol car Friday after he stopped a water truck that had been stolen a day earlier in Ignacio. The assailants, wearing camouflage and using automatic rifles, later wounded Montezuma County sheriff’s deputies Todd Martin, 35, and Jason Bishop, 25, after stealing another truck west of Cortez and then fleeing on foot into a canyon near Hovenweep. Bishop was released from Southwest Memorial Hospital Saturday afternoon after being treated for a minor gunshot wound to his head, hospital officials said. Martin remained in the hospital. He is expected to recover from serious gunshot wounds to his left elbow and right knee.

Lane said two sets of tracks matching those recovered by the stolen truck were found heading north at two locations in the expansive canyon.

Lane would not say whether the three were members of a militia group, but said they probably have had survivalist training. He said two of the three have misdemeanor convictions on their records, but no felonies.

"They’re outdoors people. They are not bed-and-breakfast-type guys," Lane said. "They have training with the outdoors."

And he said the three seemed to be specifically targeting police during the chase, firing close to 500 rounds of ammunition at them.

"All the shots were fired at law enforcement," Lane said. "They have had plenty of opportunities to shoot at civilians but have not done so."

But finding the three thought to be responsible has been difficult for officials who thought Monday morning that they would have the fugitives by the end of the day.

"They are hiding and trying to stay out of sight and so far they have done a good job of it," Kennell said.

"There has not been much progress," Lane said late Monday afternoon. "There are a lot of down officers right now."

But he said he was confident they would be apprehended, hopefully by Wednesday at the latest but maybe later.

"We will get them," Lane said. "You may be back here in December for the news conference that we found them, but we will get them."

Officers Monday set up a road block on Colorado Highway 666 near Dove Creek at an area known as Bug Point, questioning drivers and peering into their vehicles. At least six helicopters focused much of the search on a vast area of Cross Canyon that had been covered over the previous three days and extended farther north near Dove Creek east of the highway and west of the highway in Squaw Canyon.

Lane said about 300 officers from 45 state, local and federal and Indian agencies in four states were participating in the search.

Meanwhile, FBI agent Doug Beldon reported in Albuquerque that agents were investigating similarities to the robbery of the Taos Indian Pueblo gambling casino and two bank robberies in Angel Fire, 25 miles east of Taos.

"It’s very speculative," Beldon said. "It’s the sort of thing we routinely look into due to a few similarities."

He said the similarities are in the general description of the robbers and their weapons.

The Indian casino was robbed in January 1997 by three men. The FBI said two carried assault rifles and another had a stainless steel semiautomatic pistol.