A case of apparent vandalism has turned into a murder investigation. A Council Bluffs woman was killed last night in Omaha, when police say someone dropped a concrete block from an interstate overpass. 34-year-old Michelle Fergus was riding in a car her fiance was driving, when the block plunged from a pedestrian bridge over Interstate 680. Police spokeswoman Cathy Martinec says it was apparently a block from a retaining wall. Martinec says it was almost a freak incident. It hit the car and went inside, a very rare thing, though they’d recently had reports in that Omaha neighborhood of people throwing rocks at cars in that location. Because of the woman’s death and the nature of the incident, police began a homicide investigation but Martinec stops short of saying murder charges will be filed. It most likely was done not intending to cause a death, and if some kid was throwing things at cars not intending to hurt anyone, they should come forward and help police clear the case up. The retaining-wall-type block smashed through the car’s windshield and hit Fergus in the head. She was dead by the time the driver, her fiance, got her to an Omaha hospital. There have been no arrests.