For 170 years, no inmate had managed to break out of the maximum security wing of New York's Clinton Correctional Facility, tucked high in the Adirondack Mountains near the Canadian border.
But now, red-faced officials are looking for two convicted killers who escaped in a most dramatic fashion - by using power tools to cut through the walls of their cells and crawling through a maze of underground pipes and shaft to freedom.
In their place, the pair left decoys to trick guards into thinking they were asleep in their bunks -- and a yellow sticky note with a smiley face. It read, "Have A Nice Day!"
Despite a $100,000 reward and a manhunt involving some 250 law enforcement officials, Richard Matt and David Sweat -- both dangerous men who were serving lengthy sentences -- were still on the loose early Monday.
"They could be literally anywhere," said Maj. Charles E. Guess of the New York State Police, which is leading the search.
Tricking the guards
People call the Clinton Correctional Facility in Dannemora, New York, "Little Siberia."
That's in part due to its remote location -- in the sparsely populated northeast corner of New York, about 25 miles from the Canadian border.
And also because it's situated in a region where wintry weather can persist more than half the year.
The facility has prison population with 2,689 inmates. And two of its most notorious inhabitants were Richard Matt, 49, and David Sweat, 35.
Matt and Sweat apparently were last seen at 10:30 p.m. Friday during a standing count -- head counts that are performed every two hours throughout the night when guards visually check to see whether inmates are in their bunks.
The pair tricked the guards by arranging things in the bunks to look "like people were sleeping ... with these sweatshirt hoodies on," New York Gov. Andrew Cuomo said.
The inmates -- who occupied side-by-side cells -- apparently cut through a steel wall using power tools.
Once they were out of their cells, they then followed a catwalk down an elaborate maze of pipes until they emerged from a manhole outside the prison walls.
They evaded detection for some seven hours, until the inmate count 5:30 a.m. Saturday.
Along with the taunting sticky note, the pair also left a host of unanswered, and uncomfortable, questions for law enforcement.
How did they get the power tools? How could they have known the layout of the bowels of the old prison? Did they have help from the inside?
Cuomo, who toured the escape route Sunday, said it was possible the tools came from workers performing regular maintenance on the 1845 facility.
"It was elaborate, it was sophisticated," he said of the plot. "It involved drilling through steel walls, steel pipes."
The danger the two men pose can't be overstated, officials said.
Sweat was serving a life sentence without parole in the killing of Kevin Tarsia, a sheriff's deputy in 2002.
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.
"These are dangerous people," Cuomo said. "And they're nothing to be trifled with."
Sweat is white, 5 feet, 11 inches tall and weighs 165 pounds. He has brown hair, green eyes and tattoos on his left bicep and his right fingers.
Matt is white, 6 feet tall and weighs 210 pounds. He has black hair, hazel eyes and several tattoos: "Mexico Forever" on his back, a heart on his chest and left shoulder, and a Marine Corps insignia on his right shoulder.
Matt is also well known to Mexican authorities. In 2007, he was extradited from Mexico back to New York on a decade-old murder charge, documents show.
With the facility's proximity to Canada, and with Matt's ties to Mexico, authorities on both international borders have been alerted.
'No stone unturned'
Officers used roadblocks and bloodhounds and and went door to door in their search for the men. They scoured the woods and sifted through the dozens and dozens of tips that came in.
But so far, no luck.
They don't know if the pair is still together, had help on the outside, or if the men had access to a vehicle.
On Sunday, the U.S. Marshals Service issued federal arrest warrants for the escapees. The warrants clear the way for the federal government to involve its considerable resources in the manhunt.
"Every resource available to us will be used in bringing these two men to justice," said William O'Toole, a U.S. Marshals Service spokesman.
Also Sunday, Cuomo announced a $100,000 reward for information leading to the pair's capture.
"We're leaving no stone unturned," Guess of the New York State Police said Sunday.
By Saeed Ahmed
CNN's Kevin Conlon, Mark Morgenstein, David Shortell, Kevin Bohn, Ralph Ellis and Holly Yan contributed to this report