David Sweat spent months exploring the tunnels under the Clinton County Correctional Facility where he was serving a life sentence before making his daring escape with Richard Matt in June. Sweat has revealed the details of how he got out to investigators. He says that almost every night between 11:30 pm and 5 am he would enter the tunnels from a hole he sawed in his cell wall and used tools like a sledgehammer to search for a route that would lead outside. Sweat was captured after three weeks on the run, and his co-conspirator was killed by a federal agent. An investigation into the prison and the Corrections Department is ongoing.