Authorities say 26 year old Jacob Carney of Surry was taking part in a supervised work detail at a farm close to the Bolduc Correctional Facility in Warren.
The crew was returned to the prison around 3:30, but it wasn't until about an hour later when they noticed Carney wasn't with them.
Police began looking for him and found him around 9:00 last night about 9-miles away at business in Rockland.
They're not sure how he got there or how his escape was undetected for so long.
Carney was serving a sentence for theft charges.
He has since been moved to the more secure Maine State Prison and is likely to face escape charges which could add several years to his sentence.