An incident report on a double-fatal boat accident on Lake Winnebago last month indicates alcohol use was a contributing factor. Sisters Lauren and Cassie Laabs were killed when two boats slammed into each other in the Town of Vinland. The report indicated both boat operators “had been drinking.” It also cited a “navigation rules violation” as a contributing factor. The sisters were ejected from the boat and neither was wearing a life jacket. A family dog was also killed.