Joyce Mitchell, the female prison employee who has been questioned in connection to the escape of convicted murderers Richard Matt and David Sweat in upstate New York, was planning to drive their getaway car, government sources tell NBC News. She got cold feet at the last minute, however, and instead checked into the hospital with “a case of nerves.” The sources add that she will be charged for her role in the escape. Meanwhile, police shut off a major highway overnight to expedite the search for the two men. “Route 374 is likely to remain closed through the morning,” the New York State Police said in a statement. The highway runs through Cadyville, a few miles from the Clinton Correctional Facility. Authorities are urging residents of nearby communities to stay indoors and to turn on exterior lights.