On July 6, 1972, deWilde was in Denver, Colorado, for a stage production of "Butterflies Are Free". He was killed in a traffic accident in the Denver suburb of Lakewood. DeWilde was driving a camper van that went off the roadway, struck a guardrail and then a parked truck. DeWilde was alone in his vehicle and not wearing a seatbelt. His camper rolled onto its side and pinned him in the wreckage. He was taken to St. Anthony Hospital, where he died at 7:20 p.m. of multiple injuries that included a broken back, neck, and leg. He was thirty years old.