DANNEMORA, N. Y. -- Investigators think a woman who worked with Richard Matt and David Sweat at the Clinton Correctional Facility planned to pick up the convicted killers after they escaped but changed her mind at the last minute, a source familiar with the investigation tells CNN.
Joyce Mitchell went to a hospital this weekend because of panic attacks, the source said.
Mitchell is one of several prison employees who has been questioned in the case, but she has not been charged. She has given a statement and is being "somewhat cooperative," a source said.
Her cell phone was used to call several people connected to Matt, another source with knowledge of the investigation told CNN. It's unclear who made the calls or when the calls were made.
Authorities are trying to determine whether Mitchell was aware her phone was being used.
Her son, Tobey Mitchell, has come to her defense.
"She's 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 told NBC.
He said his mother went to a hospital with severe chest pains about the time of the escape.
Authorities are scouring farms and fields in upstate New York after two possible sightings of the escapees by residents.
The first came in Dannemora, the same town as the prison, after midnight Friday -- not long after the inmates' escape.
One resident said he confronted one of the two men, not realizing at the time who he might be dealing with.
"I go look at him (and) I say, 'What the hell are you doing in my yard? Get the hell out of here,' the resident told ABC's "Good Morning America."
The two trespassers complied, one apologizing and saying he was on the wrong street. The resident now believes the men were actually Matt and Sweat.
The second possible sighting came overnight Monday into Tuesday in Willsboro, a town about 40 miles southeast of Dannemora.
A resident spotted two suspicious men walking down a road in a torrential rainstorm in an area marked 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."
Elizabeth Ahern lives in Plattsburgh, about 5 miles from the prison. She said residents in the normally calm community aren't taking any chances.
"It's a scary situation," Ahern told CNN's "New Day." "We are now closing our doors and locking them, and making sure we have knives and guns ready to go, just in case."
The escape tools
Matt and Sweat's escape was extraordinarily complex. 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.
"They had to have help," law enforcement veteran Matthew Horace said. "I wouldn't be surprised if, when this all pans out, there's more than one, two, three or five people that helped them on the inside."
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 an extremely loud sound -- as well as a very detectable odor.
Peñuelas demonstrated using a torch to cut open steel -- a process that was much quieter and produced no odor. But a torch would require tanks of mixed gases.
Potential and past accomplices
Anyone assisting the killers can face prison time themselves.
An accomplice who helped introduce nondangerous contraband into the prison could be convicted of a misdemeanor. But the punishment is much more serious for anyone hindering prosecution by providing criminal assistance to either of the two men. That offense is punishable by up to seven years in prison.
A former accomplice of Matt's said the escapee is the epitome of "evil."
Lee Bates, who drove a car carrying one of Matt's victims, testified against Matt and now worries about revenge. He was scared of Matt during their crimes and was scared of him now.
He described Matt's 1997 killing of a businessman in an attempt to get money.
"Torture is probably an understatement," Bates told CNN's Anderson Cooper. He said Matt shoved a knife sharpener in his victim's ear, broke his neck 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."