(AP) -- Investigators believe a female prison employee had agreed to be the getaway driver in last weekend's escape by two killers but never showed up, a person close to the case told The Associated Press on Thursday.

The manhunt, meanwhile, dragged into a sixth day with a renewed burst of activity by searchers in the woods close to the prison after bloodhounds were said to have picked up the convicts' scent. And Gov. Andrew Cuomo said investigators are also "talking to several people who may have facilitated the escape."

David Sweat, 34, and Richard Matt, 48, used power tools to cut through steel and bricks and crawled through an underground steam pipe, emerging from a manhole outside the 40-foot walls of the maximum-security Clinton Correctional Facility in Dannemora, about 20 miles south of the Canadian border, authorities said.

The person close to the investigation said authorities believe Joyce Mitchell -- an instructor at the prison tailor shop, where the two convicts worked -- had befriended the men and was supposed to pick them up Saturday morning, but didn't.

The person said that was one reason the manhunt was focused so close to the prison. The person was not authorized to discuss the investigation and spoke on condition of anonymity.

Mitchell has not been charged. Her son Tobey Mitchell told NBC on Wednesday that she checked herself into a hospital with chest pains Saturday. He said she would not have helped the inmates escape.

Hundreds of police using dogs and helicopters blocked off a main road and concentrated their search on a swampy area just a couple of miles from the prison. Schools were closed, and residents received automated calls warning them to lock their doors, close their windows and leave outside lights on.

The governor said that investigators had received tips that the convicts were in the area, and tracking dogs had picked up the scent Thursday morning.

But he added: "Look, they could either be four miles from the prison or they could be in Mexico. Right? So you just don't know."

State Police said they bolstered the force looking for the fugitives to 500 officers from 450 a day earlier.

Law enforcement officers walking an arm's length apart were conducting a grid search through a cordoned-off area consisting of mud, woods, thick underbrush and several houses, Sheriff David Favro said. He said there had been no reports of stolen or abandoned vehicles, break-ins or abductions.

Jennifer Hilchey-Reyell, who lives on the edge of the search area, heard low-flying helicopters all night and watched state police SUVs race by all day. She said she now carries a .22-caliber gun and relies also on her pit bull, Layla.

"My dog will slow them down, and that's all I need," she said.

Authorities suspect the inmates also had help from the inside in obtaining the power tools. Guards and other staff members have been questioned, but no one has been disciplined or charged.

Cuomo warned that the law will come down hard on those in the prison system who cross the line.

"If you do it, you will be convicted, and then you'll be on the other side of the prison that you've been policing, and that is not a pleasant place to be," he said.

Matt was serving 25 years to life for the 1997 kidnap, torture and hacksaw dismemberment of Matt's 76-year-old former boss, whose body was found in pieces in a river.

Matt and an accomplice stuffed William Rickerson in a car trunk in his pajamas and drove around with him for 27 hours because he wouldn't tell them the location of large sums of money he was believed to have.

According to testimony, Matt bent back the elderly man's fingers until they broke and later snapped Rickerson's neck with his bare hands.

After the killing, Matt fled to Mexico, where he killed a man outside a bar.

Sweat was doing life without parole for his part in the 2002 killing of sheriff's Deputy Kevin Tarsia, who was shot 15 times and run over after discovering Sweat and two accomplices transferring stolen guns between vehicles.

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Virtanen reported from Albany.