In December 1978, fifteen-year-old Robert Piest disappeared after stepping outside a Des Plaines, Illinois pharmacy to speak with a contractor named John Wayne Gacy. What investigators found beneath the floor of Gacy's home in Norwood Park Township led to the conviction of one of the most prolific serial killers in American history, with 33 confirmed victims. Decades later, one victim still has no publicly confirmed name, and the Cook County Sheriff's DNA initiative continues to seek family references that could finally close the last file.

Anyone with information about a family member who disappeared in the Chicago area during the 1970s and may be connected to this case is encouraged to contact the Cook County Sheriff's Office at 1-800-333-4847.