Matthew Vonderau was killed in a single car accident when the truck he was driving went off the road, hit some trees, and flipped on County Rd 1 near Hickory Gate Dr. Vonderau was ejected from the truck, which means either he was not wearing his seatbelt or his seatbelt failed. Ejection – or worse, partial ejection – is the most common cause of death in a rollover accident.