ALBUQUERQUE, N.M. - The search for two men who escaped from a private Arizona prison and their suspected accomplice has turned to the vast Yellowstone National Park area after one of the inmates was linked to a double homicide in New Mexico and efforts to find them intensified.

The U.S. Marshals Service said Sunday information developed within the past two days indicates Tracy Province, John McCluskey and Casslyn Welch may be hiding in portions of the park that span Montana and Wyoming. The agency also said investigators believe Province has separated from McCluskey and Welch. It doesn't appear any of the three are expert campers or have wilderness survival skills, said Thomas Henman, supervisory deputy with the U.S. Marshals Service in Phoenix.

"From the start, we believed these individuals would be staying at campgrounds and truck stops and other places like that. This keeps to that pattern," Henman said. He added authorities believe the three might be sticking to back roads and smaller state highways.

Federal investigators in Montana and Wyoming and law enforcement authorities with the National Park Service are working with investigators from Arizona to follow leads in the Yellowstone area.

The manhunt for the three intensified Saturday after forensic evidence linked at least one of the inmates to the killings of an Oklahoma couple who was traveling through eastern New Mexico earlier this week.

The badly burned skeletal remains of Linda and Gary Haas - both 61 and from Tecumseh, Okla. - were found in a charred camper Wednesday morning on a remote ranch in Santa Rosa. The couple's pickup truck was found that afternoon 100 miles west in Albuquerque.

"They are very dangerous individuals, very desperate individuals, and the longer they're out there, the more desperate they become and the more dangerous they become," Henman said Sunday.

Province, McCluskey and Daniel Renwick escaped from the medium-security Arizona State Prison near Kingman on July 30 after authorities say the 44-year-old Welch of Mesa threw wire cutters over the perimeter fence. Welch is McCluskey's fiancee and cousin.

Renwick was arrested Aug. 1 in Colorado.

The three later kidnapped two semi-truck drivers at gunpoint and used the big rig to get away, authorities said. The group left the drivers unharmed in the truck at a stop just off Interstate 40 in Flagstaff and then fled.

Province was serving a life sentence for murder and robbery out of Pima County, Ariz. McCluskey was serving a 15-year prison term for attempted second-degree murder, aggravated assault and discharge of a firearm out of Maricopa County, Ariz. Renwick had been serving a 22-year sentence for second-degree murder.

Authorities said the movements of the two inmates and their accomplice have been unpredictable so they will continue with the nationwide manhunt until all three are arrested. Publicizing their photographs in newspapers and on television, including a segment Saturday night on "America's Most Wanted," has helped generate tips, investigators said.

A series of billboards featuring the three are also planned.

"We're hoping the right lead will come in and we'll be able to move quickly on it," Olson said.