They didn't work nights. She and Lyle worked the same shift, days, and drove both ways together in the same car. On the way home from work they had dinner then she got chest pains so he took her to the hospital where she spent the night and he went home.
http://abcnews.go.com/US/husband-pr...ll-accused-helping-convicts/story?id=31865459
"On the night of the escape, Dumas said, the couple left work, "drove through town, stopped at the Chinese restaurant here in town, had dinner, drove home. As they were driving home Joyce said she was having some chest pains, some flushing in her face, so he decided he was going to take her to the hospital."
According to Clinton County District Attorney Andrew Wylie, Joyce Mitchell had planned to meet Matt, 48, and Sweat, 35, at a power plant near the prison the night of their escape and expected to drive them to a wooded area about seven hours away. In addition, Joyce Mitchell had talked to Matt and Sweat about killing her husband, who also worked at the prison, Wylie said.
In the end, though, instead of driving the getaway car, Mitchell checked herself into a hospital, complaining of a panic attack, Wylie said. "
"When Lyle Mitchell got back home from the hospital, he "slept for about four hours, came back to the hospital and spent the morning with Joyce," Dumas said. "Subsequently, the police started contacting him, started asking some questions. At that point, he didn't realize Joyce was involved. He just thought they were just following up on all the employees in the area." "