South Bend police are investigating the weekend death of a Michigan man killed when his dune buggy crashed during a "mud bog" race at the St. Joseph County 4-H Fairgrounds.

Forty-eight-year-old Steven DeLeeuw of West Olive, Mich., was pronounced dead Saturday night at a South Bend hospital after his vehicle flipped several times and crashed into a concrete barrier and chain-link fence at the fairgrounds.

DeLeeuw, who suffered massive blunt force trauma, had been competing in a "Summer Thunder Mud Bog" event.

WNDU-TV reported a forensic mechanic will begin analyzing DeLeeuw's vehicle Monday to determine if the crash was caused by operator or mechanical error.

Police said DeLeeuw was wearing a helmet and safety harness at the time of Saturday's crash, which was witnessed by his 15-year-old son.