The investigation into the deadly chain-reaction crashes on Bulgaria's Trakia highway is examining the role of dense fog, vehicle speeds, road conditions and driver behavior, while the National Investigation Service (NIS) has deployed a team of 10 investigators to establish how the collisions occurred. The crashes involved more than 80 vehicles and left 11 people dead and dozens injured. Forty-four witnesses have already been questioned, and Yambol District Prosecutor Doychin Doychev said further interviews were planned....