Thomas Kelley, 51, is a convicted car thief who had been at Donovan State Prison since November for a parole violation.
Kelley, who worked as a firefighter at the prison, was discovered missing Sunday night.
At about the same time, a fire engine was reported 10 miles away and it was being driven erratically. Deputies pulled the fire engine over, but Kelley ran off.
Kelley was scheduled to be released in December 2013.