Autopsy results show Jeffery Cheek, 44, died from electrocution, according to Marlboro County Coroner Tim Brown.
Cheek's body was found in the boiler room at Marlboro County High School about 8 a.m. Wednesday.
Cheek was a sub-contractor for the school.
Students were kept in class Wednesday morning until police and the coroner cleared the scene. Students were on an alternate schedule, but school were dismissed at regular time.