NEW YORK -- There's almost no doubt someone helped the killers get out. The question is who.
Richard Matt and David Sweat have been on the run for more than three days now. The convicted murderers apparently used power tools to cut out of their cells at the Clinton Correctional Facility in upstate New York, navigated a complex maze of pipes and popped out of a manhole, one block away.
Female employee questioned
An employee who tailored clothing at the prison is being questioned as a possible accomplice, a law enforcement source briefed on the investigation told CNN on Monday.
The woman knows the two escapees "very well," the source said.
While the woman has not been arrested nor charged, criminologist Casey Jordan said the notion of a female employee succumbing to male inmates is certainly possible.
"I don't want to admit that it happens, but I know women who have met men in prisons working there, and fallen in love, and quit their jobs and married them when they got out," Jordan said.
"We call this, very often, hybristophilia. It is the psychological phenomenon where women are attracted to a bad boy. And sometimes the worse he is, the more deep the attraction."
Matt and Sweat are indeed some of the worst of the worst.
Matt was convicted on three counts of murder, three counts of kidnapping and two counts of robbery after he kidnapped a man and beat him to death in December 1997, state police said. He was sentenced to 25 years to life in prison.
But he is also a veteran of prison breaks. In 1986, he escaped from an Erie County jail, the New York governor's office said. Upon his capture, Matt was sent to a maximum security prison in Elmira, New York, on charges of escape and forgery. He was released from the Elmira Correctional Facility in May 1990.
Sweat was serving a life sentence without parole for killing sheriff's deputy Kevin Tarsia in 2002.
The slain deputy's brother, Steven Tarsia, said knowing Sweat is on the loose is "like living the nightmare over again."
"I just hope he doesn't come back here," he said.
A well-planned escape
The complexity of the escape has astonished prison experts and Gov. Andrew Cuomo, who toured the inmates' escape route.
"It was really unbelievable," Cuomo said. "If it was a movie plot, you would say that it was overdone."
He said the inmates cut through a cell wall that included steel a quarter-inch thick, 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, shimmied their way through the steam pipe, cut another hole so they could get out of the pipe, and finally surfaced through a manhole.
"This is one of the great escapes ... that I've ever seen," said bounty hunter Duane "Dog" Chapman, who has been working for over 35 years. "If they did as much planning to get away as they did to get out of the prison, they're gone."
Phantom power tools
One enormous question is how Matt and Sweat got hold of power tools. Another is why guards didn't hear the power tools being used.
Cuomo said it's possible the tools came from contractors performing maintenance work on the 170-year-old prison in Dannemora. The company that employs the maintenance workers has been cooperating with the investigation, New York State Police Maj. Charles Guess said.
Another theory: Perhaps the female employee who worked on inmates' clothing hid power tools in bundles of clothes, said Larry Levine, a former federal inmate and founder of Wall Street Prison Consultants.
As far as why guards apparently didn't hear the power tools being used, CNN law enforcement analyst Tom Fuentes said it's possible the cutting took place during the daytime -- when noise from the maintenance workers may have drowned out the sound.
Staying under the radar
The governor announced a $100,000 reward for information leading to the capture of Matt and Sweat. But experts say the two men will do everything they can to stay under the radar.
"You know how you feel when you run a red light and you see a cop right there, you panic? Times 10, that's what they feel like right now," Chapman said.
He said he's confident the two killers will get caught -- but when that happens, officers will need to be extremely careful.
"These kinds of guys here will hold court in the street," he said. "They have nothing to lose."
Lessons for prisons
No one had managed to escape from the maximum security part of Clinton Correctional Facility in its 170-year history -- until this past weekend.
Levine said the prison break should prompt older prisons to upgrade their infrastructure -- perhaps by installing wall sensors and motion sensors.
Chapman said even prisons that have never had an escape should be on alert.
"Whatever a man can build, a man can break."
CNN's Don Lemon, Shimon Prokupecz, Alisyn Camerota and David Shortell contributed to this report.