Investigators are still trying to figure out what caused a deadly crash in Union. They say a man was killed Tuesday afternoon when a man lost control of his suv on route 27. It ended up striking a guardrail before coming to rest in some trees. The Knox County Sheriff's Department says a passing motorist noticed the vehicle and 37 year old Chris Lafrance was found inside.He was already dead by the time rescuers arrived. Police are considering whether a medical condition caused Lafrance to lose control. .