BERRIEN COUNTY, Ind. -- A semi-truck driver is in critical condition after a rollover crash in Berrien County.

This happened June 3 on US Highway 12 near I-94 and the exit four off-ramp. The Berrien County Sheriff's Office the truck was delivering coal to Burns Harbor, Indiana. Officers freed 67-year-old Billy Gibbs of Southgate from the wreckage. He was later air-lifted to University of Chicago Medical Center in critical condition. 

Investigators believe the crash was caused by speed. There are also indicators that Gibbs suffered a medical emergency at the time.