Catherine "Cathy" Davidson went missing just after her family arrived at the State Park from Chicago for a picnic on September 1, 1973. Cathy and the other children had gone off to explore a creek the empties into Lake Michigan, while the parents unpacked their car. When the children returned Cathy was not with them. This sparked a multi-day search for her without turning up anything other than a pair of green panties. It is unclear if these belonged to Cathy or not. She was last seen wearing a white blouse, blue shorts and white sandals