Updated

An escaped con, once accused of plotting to kidnap David Letterman's son, was captured Wednesday after six days on the lam.

Lake County Sheriff Lucky Larson confirmed Wednesday that Kelly A. Frank, one of two Montana State Prison escapees wanted since Friday, is in custody, but the other remains at large.

Undersheriff Jay Doyle and a deputy arrested Frank while on patrol as part of a search for the inmates, Larson said. He said the officers "took him down," but he did not immediately provide other information about the nature of the arrest.

It happened along Montana 35 between Polson and Bigfork on the east shore of Flathead Lake. Frank was arrested on the west side of the Mission Mountains and had been seen Tuesday on the east side.

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U.S. Forest Service personnel saw Frank, 45, and William J. Willcutt, 22, at about 6 p.m. Tuesday near a campground along Montana 83. Frank had once been accused of plotting to kidnap the son of talk show host Letterman, who has a ranch in western Montana.

The men fled once they realized they had been spotted, Doyle said. The Forest Service workers found, at the campground, Department of Corrections clothing plus an address book and other items that identified the men as Willcutt and Frank, authorities said.

"We have reason to believe they are scantily clad because they got jumped," Mike Mahoney, warden at the Montana State Prison near Deer Lodge, said Wednesday.

Mahoney said he gathered from talking to law enforcement officials in the Swan Lake area that "these guys looked like they had been in the river. One was out long enough to get partially dressed, but the other didn't have a chance to get much on."

The search for the two men moved to the Swan Lake area Tuesday, after a vehicle found abandoned in the woods was traced to Anaconda. The car's owner had been out of town and did not know his vehicle had been taken from his home, Mahoney said. The man also found his house had been burglarized and three weapons were missing.

After the sighting near the campground on Tuesday, about 30 to 40 people participated in a search that included checking recreational cabins, a Lake County dispatcher said.

The search continued Wednesday with officials from local, state and federal agencies. They included a Department of Corrections search team; a Flathead County SWAT team; sheriff's deputies from Missoula, Lake and Powell counties; Montana Highway Patrol troopers; tribal police from the Flathead Indian Reservation; and Forest Service and border patrol personnel.

"The searchers were out all night, with the highway patrol doing stops and vehicle checks," Mahoney said.

The search included six dogs and a U.S. Department of Homeland Security helicopter equipped with heat-seeking infrared equipment.

"We're guardedly optimistic we're going to get some action on this today," Mahoney said.

Larson said Willcutt and Frank were considered armed and dangerous. On Tuesday night the sheriff advised residents in the Swan Lake area to stay inside and lock their doors. He also advised residents to remove keys from their vehicles and immediately report any suspicious activity.

The men drove away from the prison ranch, in the Deer Lodge area, last Friday.

Prison officials and area law enforcement officers searched the mountains around the prison for four days and were aided by a Black Hawk helicopter. Except for a clue that someone may have stashed weapons and provisions for the two, the searchers came up empty handed.

Employees at a store in Clancy, near Helena, reported that a man they believed to be Willcutt stole three knives, a box of .38 caliber ammunition and food from the business at about noon Sunday.

Law enforcement officials determined there was a "good possibility" the thief was Willcutt. They said he was familiar with the Clancy area from several burglaries he committed there in 2005.

Frank was arrested in 2005 on allegations he crafted a plan to kidnap Harry Letterman and the boy's nanny for a $5 million ransom.

A charge of solicitation to kidnap was dropped in return for pleas of guilty to other charges, including felony theft and misdemeanor obstruction. Frank worked as a painter at Letterman's ranch and received a 10-year prison sentence for theft, for overcharging Letterman.

At the time of his arrest, Frank was on supervised release for a 1998 conviction for stalking and intimidating a woman.

Willcutt has been convicted of burglary, and was denied parole earlier this year.

He lived in a prison work dormitory. Frank lived within the prison and would have been eligible for parole in three months.

Both had been assigned to a working ranch operated by the prison to rehabilitate convicts.

They face additional prison sentences of up to 10 years each for escaping, prison spokeswoman Dana Eldredge said. She added that authorities don't know if the prison break was planned or a spur-of-the-moment decision.

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The Associated Press contributed to this report.