Authorities say a Kentucky federal prison inmate who started a 15-month sentence two weeks ago has died. Pulaski County Coroner Clyde Strunk tells the Lexington Herald-Leader 55-year-old John Arthur died Monday after a riding lawn mower turned over on top of him. Strunk says prison officials told him Arthur was using the mower to cut grass at the U.S. Penitentiary in McCreary County. Strunk says the machine flipped over into a pond as Arthur mowed on an embankment and trapped him underneath. Strunk hasn’t officially ruled on the cause of Arthur’s death. The U.S. Department of Justice says in a statement Arthur was found unresponsive at the facility. Strunk pronounced him dead roughly an hour later at a hospital. Arthur’s sentence for disability fraud began July 30 after he pleaded guilty in June.