DANNEMORA, NY — (CNN) Investigators think that a woman who worked with two convicted murderers at an upstate New York prison planned to pick up those men after their escape — only to change her mind at the last minute, a source familiar with the investigation told CNN.

Joyce Mitchell worked with fugitives Richard Matt, 48, and David Sweat, 34, tailoring clothing as an employee of the Clinton Correctional Facility, a maximum-security prison in Dannemora, New York, 20 miles south of the Canadian border.

She has not been arrested or charged in connection with their escape, nor has anyone else. The source added that Mitchell is cooperating with police, having provided information as needed.

Her cell phone was used to call several people connected to Matt, according to another source with knowledge of the probe. It’s not clear who made these calls, when they were made or if Mitchell knew about them.

Mitchell went to the hospital this weekend because of panic attacks, according to one of the sources. By then, authorities had discovered during a 5:30 a.m. Saturday bed check that Matt and Sweat had busted out of the prison.

Mitchell’s son Tobey Mitchell told NBC News that his mother was in a hospital Saturday evening because “she was having severe chest pains and she was concerned about that.” He added that his mom, who works at the prison with her husband, “worries a lot about everything” but strongly challenged suggestions she had done anything wrong.

“She is not the kind of person that’s going to risk her life or other people’s lives to let these guys escape from prison,” he said.

If the escapees did indeed have a designated driver, imagine their horror when they popped out of a manhole sometime late Friday or early Saturday and found no accomplice waiting.

“That must have been just a complete panic on their part … ‘Now what? Where are we going to walk to — this small, rural area?’ ” said CNN law enforcement analyst Tom Fuentes, a former FBI assistant director. “It’s going to be hard to hide day or night for very long, and they wouldn’t have been prepared to deal with the elements.”

They’d have to find food, water and money, while also trying to get their hands on weapons or a vehicle.

“That would put every family in that rural (North Country) in extreme danger,” Fuentes said. “If they’re feeling like cornered animals out there, they are going to do something drastic to try to ensure their physical survival and their continued freedom out of that prison.”

Without any help like a getaway driver, someone who escapes from there can easily get lost, said Jeff Hall, who teaches at the City University of New York and did his dissertation on northern New York prisons.

“The environment is formidable,” said Hall, who grew up near the Dannemora prison, where his father worked. “It’s rough terrain and, if you’re not familiar with it, it can be deadly.”

There have been two possible sightings of the escapees in upstate New York.

The first came in Dannemora after midnight Friday — about five hours before authorities discovered they had escaped.

A resident there told ABC’s “Good Morning America” he confronted two men, whom he didn’t know then but now believes to be Matt and Sweat, walking in his yard and told them to leave. One of the men was carrying what appeared to be a guitar case, a woman who saw this unfold told ABC.

Authorities haven’t commented on this report, though New York State Police said that law enforcement will search homes Wednesday in Dannemora.

“These searches are not the result of a new lead; law enforcement (is) retracing steps made early in the investigation,” police said.

Another focus in about 40 miles southeast in Willsboro, a town of about 2,000 people along Lake Champlain.

That’s where a resident spotted two men overnight Monday walking in a torrential rainstorm on a road surrounded by large farms, fields and wooded lots, Willsboro Town Supervisor Shaun Gillilland said. As the witness’ car approached them, they took off.

“They were walking down the road, not dressed for the elements,” Gillilland said. “They ran into the fields, from what I understand. So this behavior … was suspicious.”

Both reports could be false leads, as often happens in manhunts. Former U.S. Marshal Service regional commander Lenny DePaul said he thinks it’s important that people be on the lookout.

Still, authorities are clearly focusing on the rural swath of New York near Vermont and the Canadian province of Quebec.

“If members of the public see anything unusual upon arriving at their residence or seasonal homes, they are asked to contact law enforcement immediately,” the New York State Police said Wednesday, “The State Police have deployed all available assets in an effort to ensure the safety of the public.”

Matt and Sweat’s escape was so extraordinarily complex that experts says the two must have had help.

Using power tools, they cut through a cell wall that included a steel plate, maneuvered across a catwalk, shimmied down six stories to a tunnel of pipes, followed that tunnel, broke through a double-brick wall, cut into a 24-inch steam pipe, climbed through the steam pipe, cut another hole so they could get out of the pipe and finally surfaced through a manhole.

Aside from the mystery of how they got the necessary power tools, many wonder how they could have used them without detection.

The hole in the cell’s steel wall suggests they used a cutoff wheel, ironworker Ernesto “Ernie” Peñuelas said. But using that tool would have produced a loud sound and detectable odor.

The fugitives’ pasts are even more worrisome.

Sweat was serving a life sentence without parole for fatally shooting and then running over Broome County Sheriff’s Deputy Kevin Tarsia in 2002.

Matt was convicted for kidnapping a businessman for 27 hours and — when he didn’t comply with his pleas for money — killing him.

“Torture is probably an understatement,” Lee Bates, who drove a car carrying one of Matt’s victims, told CNN’s Anderson Cooper of the 1997 killing. He said Matt shoved a knife sharpener in his victim’s ear, broke his neck and then dismembered the body.

Despite his violent past, Matt is capable of getting others to help him, Bates said.

“He can make friends easy. He’s a master manipulator.”

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