Police think the Stockton serial killer may have killed two people in Chicago. The two police departments are working together to look at whether two Windy City cold cases are tied to the serial killer. Officers are also working with Chicago Police to see if two murders there in 2018 are connected. Video of the Chicago suspect led him to be dubbed “The Duck Walk Killer” because of his walk. Video of the Stockton killer is similar. The Stockton killer is linked to the deaths of six men and injury to one woman.