The Rock County Sheriff’s Office is investigating a fatal, single-vehicle roll-over traffic crash. Authorities say the crash happened about 9:00 Wednesday night on Highway 104 just north of Atkinson Road. Investigators say a 66-year-old Monroe man was driving north and crossed the center line into the southbound lane. He then swerved back into the northbound lane, over-corrected and lost control. The car went into the ditch on the east side of the road and hit a limestone wall spinning clockwise and coming to rest on its passenger side. Deputies say the driver was not wearing his seat belt and was ejected form the vehicle. He was the lone occupant of the car. The road was closed for four hours as the Rock County Sheriff’s Office Reconstruction Team investigated.