Hundreds of law-enforcement officials are involved in the search for the convicts, which extends to Canada and Mexico as well as the US.
Authorities believe the convicts planned to escape to an area that is about a seven-hour drive from the prison, but it's now unclear where they might have gone.
Richard Matt, 48, was serving a sentence of 25 years to life for killing and dismembering his former boss in 1997. David Sweat, 34, was serving a life sentence for killing a sheriff's deputy.
Joyce Mitchell, the prison tailoring shop instructor who helped the inmates escape by providing them with tools and had agreed to drive the getaway is due to appear in court on Monday morning.
She had befriended the prisoners but backed out at the last minute because she felt guilty. "Basically, when it was go-time and it was the actual day of the event, I do think she got cold feet and realized, 'What am I doing?'" Clinton County District Attorney Andrew Wylie said Sunday.
Here's what we know so far about the two criminals and their escape from Clinton Correctional Facility:
The men are thought to be highly dangerous. Detective Gabriel DiBernardo told The New York Times that "you can never have enough security with" Matt or "turn your back on him" because of his great efforts to elude police. Matt escaped from a jail in Erie County in 1986.
Police are investigating whether the convicts had inside help in escaping. Authorities have charged 51-year-old Joyce Mitchell, who works as an industrial-training supervisor in the tailoring department, with criminal facilitation and promoting prison contraband. They believe Mitchell had a personal relationship with Matt.
Joyce Mitchell
(REUTERS/Mike Groll/Pool) Joyce Mitchell (L), suspected of having smuggled contraband into the prison where convicts Richard Matt and David Sweat escaped last weekend, is arraigned in City Court in Plattsburgh, New York June 12, 2015.
The escape was elaborate, as acting state corrections commissioner Anthony Annuci said Saturday at a news conference: "They went onto a catwalk which is about six stories high. We estimate they climbed down and had power tools and were able to get out to this facility through tunnels, cutting away at several spots." They then reportedly came out of a manhole outside prison walls.
Officials believe the two men had cellphones in the prison, likely provided by Mitchell, and rehearsed their plan before carrying it out.
Authorities believe that Mitchell had planned to meet Matt and Sweat near the manhole to drive them to an area about seven hours away from the prison, but she backed out at the last minute and checked herself into a hospital for "nerves," CNN reports.
prison break
(Darren McGee/New York State Governor's Office, via AP) This photo provided by New York State Governor's office shows Gov. Andrew Cuomo on a catwalk looking into the cell that inmates escaped from at a maximum-security prison near the Canadian border in Dannemora, New York.
Matt and Sweat used hacksaws to cut through steel walls around air vents near their cots to create the hole they would escape through, according to the New York Daily News. They'd put the vents back in place as they were doing this work, which might have taken place over a period of days or weeks, to avoid detection.
Mitchell might have also provided the convicts with eyeglasses with lights attached to them to help make their escape, according to authorities.
To power the tools they used to cut through the steam pipes they crawled through to escape, Matt and Sweat used extension cords and hot-wired electrical junction boxes, according to the Daily News.
To keep prison guards from figuring out they were gone, the duo reportedly stuffed their beds with clothes to make it look like they were there. Corrections officers are supposed to do bed checks every two hours, according to The New York Times. The inmates were reportedly discovered missing at a 5:30 a.m. bed check on Saturday.
They left a note on one of the pipes. The yellow note had a smiley face and "have a nice day" written on it.
New York prison break
(New York State Governor's Office)
Matt and Sweat were being held in an "honor block" of the prison, according to the Daily News. They were reportedly allowed to spend most of their time outside of their cells and working in a shop where they might have been able to gather the tools they used for their escape.
The prison was undergoing construction work that contractors were brought in to carry out. Prisons have less control over contractors than they do over permanent staff members, Martin Horn, former commissioner of the New York City Department of Correction, told Business Insider. "Outside contractors may or may not comply with [the protocols]," he said. "A worker might be reluctant to report the tool as being lost over fear of losing their job."
A source told the Daily News that prison guards would inspect the vehicles of contractors for contraband and prisoners hiding out, but would not keep a close watch over the tools the contractors had.
Clinton Correctional Facility
(Google Maps/Skitch)
Two witnesses reported seeing Matt and Sweat in their backyard after the pair escaped, according to ABC News. The backyard is near the manhole the men reportedly came out of. When the witnesses confronted the men, one of them reportedly said: "We're just lost. We don't know where we are. We're on the wrong street." They then both took off running, the witnesses said.
The witnesses reportedly saw the men carrying a guitar case, which authorities believe the men used to carry the power tools that cut through the pipes.
New York prison break
(New York State Governor's Office) The manhole the prisoners reportedly escaped from.
