David Sweat spent six months planning his escape from a New York prison, roaming around the prison's walls and underground tunnels scouting an escape route, he told investigators following his capture.

His plan had allegedly been in the works for quite some time but his efforts only seriously began after he was transferred to a cell next to Richard Matt in late January, according to the New York Times. Almost immediately he used a hacksaw, which was smuggled into the prison inside a package of hamburger meat, to cut a hole in the back of his cell and then cut through the back of Richard Matt's cell.

From that point on, at 11:30 pm each night, Sweat climbed down pipes that went down several stories and roamed underground tunnels for almost six months before his escape. He would return to his cell each morning before the 5:30 count, camouflage the opening and go about his daily prison routine, according to ABC News.

According to his own account, Sweat acted like MacGyver, even rigging a fan from his cell using electricity from the tunnel's lights, according to the New York Daily News.

After months of searching, Sweat finally found a series of tunnel pipes that led to the streets of Dannemora, NY. He tried to chipping away a concrete tunnel wall with a variety of tools, but all his attempts proved fruitless.

Around May 4, Sweat caught a break and discovered a shortcut. Using a hacksaw blade with a rag as a handle, Sweat began cutting through a heating pipe that had cooled down as the season changed. It took four weeks to cut holes large enough for him and Matt.

Upon finally having a route to the outside world, the prisoners did a dry run before making their real escape on June 6.