Armed with a complex plot and power tools, the pair did what no one else has been able to do in the 170-year history of New York state's most populated prison - escape from its maximum security walls.
Now, as authorities look for the men in three countries, many are left scratching their heads.
Here's what we know and don't know about their scheme:
The tools
What we know: Matt and Sweat, who lived in adjacent cells, apparently used power tools to cut through a concrete-and-steel wall at the Clinton Correctional Facility in Dannemora, New York, authorities said.
What we don't know: How in the world they got those power tools -- and how guards didn't hear them being used.
New York Gov. Andrew Cuomo said the prison, built in 1845, undergoes regular maintenance, so it's possible the tools came from workers who are often in the facility.
The company who employs the maintenance workers is cooperating with the investigation, New York State Police Maj. Charles Guess said.
