Two teenagers from Michigan may be added to the list of victims of serial killer John Wayne Gacy.

The Cook County Sheriff’s office continues to investigate cold-case files from around the country, especially from the 1970’s when Gacy was in the midst of his murder spree.

Sheriff Tom Dart says his investigators will try to get DNA evidence from two boys who were raped and killed in Michigan; and they’ll study Gacy’s own travel records  to see whether he was there at the time.

The sheriff has yet to name the boys.