Convicted killer Tracy Province told authorities he was relieved that the manhunt was over for him when he was arrested around 6:20 a.m. in Meeteetse, Wyo., about 60 miles outside of Yellowstone National Park, said David Gonzales, the U.S. Marshal for Arizona.
The other inmate, John McCluskey, as well as suspected accomplice Casslyn Welch, were still on the lam.
"They consider themselves as Bonnie and Clyde," Gonzales said. "This is very, very serious business."
Gonzales said agents were working on leads in Wyoming. He said they believed that McCluskey and Welch were no longer in tourist-packed Yellowstone, where more than 100 armed park rangers were patrolling amid an estimated 30,000 campers and tourists.
At the park's northern entrance at Gardiner, Mont., rangers were given posters of the fugitives so they could check the passing cars. But they weren't handing out the posters, nor were they advising entering motorists about the search.
Authorities tracked Province to the town with a resident's help. On Sunday, the woman chatted briefly with Province on the steps of the church, Gonzales said. She called police after recognizing him on television.
When marshals and other law enforcement officers arrested him, he initially denied being Province, Gonzales said. He was carrying a 9 mm handgun and the sign that said "Casper," authorities said.
Province was at the Meeteetse Community Church at least an hour before the 10:30 a.m. service Sunday, said Jay Curtis, who plays drums for the nondenominational Christian church and welcomed Province.
Province sang along with the music, especially a song titled "You're Grace is Enough," Curtis said.
Efforts to find the trio intensified after they were linked to a double homicide in New Mexico.
Province, McCluskey and Daniel Renwick escaped from a private, medium-security Arizona State Prison near Kingman on July 30 after authorities say the 44-year-old Welch threw wire cutters over the perimeter fence. Welch is McCluskey's fiancee and cousin.
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. Renwick was arrested Aug. 1 in Colorado.
The manhunt intensified Saturday after forensic evidence linked the two inmates and Welsh to the killings of an Oklahoma couple. New Mexico State Police spokesman Peter Olson declined to elaborate.
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 eastern New Mexico. Their pickup truck was found later 100 miles west in Albuquerque.
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 two consecutive 22-year sentences for second-degree murder.
Publicizing their photographs in newspapers and on television, including a segment Saturday night on "America's Most Wanted," has helped generate tips, investigators said. Gonzales said a $40,000 reward was set for McCluskey and Welch's capture.
"Rest assured, we are going to be on McCluskey like a cheap suit," Gonzales said. "We are not going to pull this thing down."
Some Yellowstone campers weren't concerned about the search, including four men from Pittsburgh who were taking a vacation. Their families called them with the news that the inmates could be in the area.
"We're just driving around, stopping and getting out of the car," Kevin Tonini said. "The odds of them being there aren't too good. It's a big park."
Volz in Gardiner, Mont., and Bob Moen in Cheyenne, Wyo., contributed to this report.