SIOUX FALLS, S.D. (KELO AM) - The South Dakota Highway Patrol has not been able to determine the cause of the crash last February that claimed the lives of four members of the Vollmer family of Sioux Falls.
Patrol Captain Kevin Joffer says investigators have ruled out medical or mechanical problems and drugs and alcohol.
Joffer says there's no evidence of adverse weather or road conditions. He says they also looked into cell phone records. Both Mr. and Mrs. Vollmer had cell phones and records show no indication that there was any use of the phones or texting that took place before the crash.
Joffer says the speed of the Vollmer vehicle prior to the crash is estimated at between 75 and 78 miles an hour.
The crash claimed the lives of Jim, Julie, Alyssa and Caleb Vollmer. A surviving daughter, Brittany, was at college in Orange City, Iowa, at the time of the crash.
Joffer says the Vollmers were returning to Sioux Falls from Salem after a basketball tournament. They were traveling in the passing lane when the vehicle drifted off the road and hit a guard rail. The vehicle spun around and went airborne crashing into a ravine