John Wayne Gacy
As of August 2017 five victims remain unidentified, five of whom had been buried beneath Gacy's crawl space, with one additional youth buried approximately  from the barbecue pit in his backyard. Experts used the skulls of the unidentified victims to create facial reconstructions. Based upon Gacy's confession, information relative to where the victims were buried in his crawl space relative to Gacy's identified victims, and forensic analysis, police were able to determine the most likely dates when his unidentified victims were killed.