Investigators say the fire which killed three members of a Davenport family earlier this week was caused by cigarettes — in the bathroom. Davenport Fire Marshall Mike Hayman.says the official cause of the fire is listed as “misuse of smoking materials.” Marshall Hayman says investigators probably will never know who was responsible as three of the family members were heavy smokers.Shirley Wiskirchen and her son and daughter-in-law were killed in the fire. The couple’s three-year-old daughter told her grandfather the house was on fire and the two escaped the blaze.