A former prison employee who admitted to helping two convicted killers escape from a maximum-security prison in northern New York, leading to one of the largest manhunts in the state’s history, was sentenced on Monday to at least two years and four months in prison.

“You did terrible things,” Judge Kevin K. Ryan of Clinton County Court told the former employee, Joyce E. Mitchell, during her sentencing hearing. “At any time, you could have stopped the escape from happening.”

Under the terms of her plea agreement, Ms. Mitchell could spend up to seven years in prison.

Ms. Mitchell, wearing a black-and-white prison uniform, wept in court and struggled to read a statement apologizing for her role in helping Richard W. Matt and David Sweat escape from the Clinton Correctional Facility in Dannemora, N.Y.

“I am 51 years old, and this is by far the worst mistake I have made in my life,” she said through tears. “I live with regret every day and will for the rest of my life.”