This comes more than 30 years after the bodies of 33 young men were found on Gacy's property.
Sheriff Dart is also urging relatives of anyone who went missing during Gacy's killing spree to submit a DNA sample for testing.
Scientific advances in DNA have made it possible for investigators to learn so much more now than when they first tried to identify Gacy's victims in the late 1970s. Back then they relied primarily on dental records. And some of the families looking for their missing loved ones had no dental records. Others never came forward because of the stigmas attached to Gacy.
Cemetery workers exhumed a coffin filled with the remains of a young man who went missing decades ago, someone likely from the Midwest, with family that never learned what became of him. He became one of John Wayne Gacy's victims but has never been identified. With the help of modern technology, more than three decades later, Cook County Sheriff Tom Dart hopes to give back his identity and give answers to the families of eight unidentified victims.
"These are eight people that deserve more," said Dart. "These are eight individuals that right now are nothing more than just forgotten people that were murdered by one of the most evil persons ever to walk the earth. They deserve this type of closure."
As part of an effort to close cold cases, the sheriff says investigators first started looking at the unidentified Gacy victims this spring.
The prolific serial killer was executed in 1994 for the murders of 33 young men, most of whom were buried in the crawlspace or on the property of his unincorporated Norwood Park home. After exhaustive effort, investigators were only able to identify 25 victims using dental records.
"The elephant in the living room was those unidentified kids," said former Gacy prosecutor Bob Egan. "You wonder about them all the time."
Attorney Richard Kling defended Gacy for several years as he fought execution in the Illinois Supreme Court. But he supports the effort to identify Gacy's victims.
"If it gives closure to one family, then I think it's important. It may not give closure to anybody, and then it would be potentially taxpayers money that was ill spent," Kling said.
The DNA profiles of the victims are just one part of solving the mysteries. Now the sheriff needs victims' family members to come forward to offer DNA samples for comparison.
"There was a lot of stigmas floating around in the 70s that don't exist now," said Dart. "We encourage people to come forward."
Sheriff Dart says the eight Gacy victims would have all gone missing between 1970 and December 1978. All were white and most were between the ages of 14 and 21.
The sheriff has set up a hotline and a website to answer questions and gather information. The number is (800)-942-1950.
INVESTIGATION TIMELINE PROVIDED BY SHERIFF DART'S OFFICE
Early 2011 - Sheriff Dart begins a new focus on the office's cold cases. The office's largest cold case investigation involves Gacy's 8 unknown victims.
April - Citing advancements in DNA work and other investigative techniques, Sheriff Dart authorizes detectives to begin researching old files and interviewing those originally involved in the Gacy case in an effort to help identify those 8 unknown victims. Investigators learn the jaw bones were buried. They also reach out to the University of North Texas laboratory about conducting the DNA work necessary to establish identities.
June - Exhumations begin to find the casket containing the eight jaw bones. After three digs with a backhoe, investigators find the casket, buried under another casket filled with infants, animal remains and other bagged medical tissue. The 8 jaw bones are in good condition and are flown to the UNT laboratory.
August - UNT lab directors notify investigators that DNA profiles have been secured for only 4 of the 8 unidentified victims. Though mitochondrial DNA has been secured from all, nuclear DNA has been secured from only 4. They will need additional bone material to secure full DNA profiles on those 4.
September - Exhumations of those 4 are conducted at Resurrection, Maryhill, Queen of Heaven and Woodlawn Memorial cemeteries. Femur bones are removed and delivered to UNT laboratory officials
October -DNA profiles are secured on six of the unknown victims, with the remaining two expected by months' end.
October - Sheriff Dart invites those who believe they are related to a Gacy victim to submit a DNA sample. Either one immediate family member or multiple secondary relatives are needed.
1970 - Released from Iowa prison on sodomy conviction
1971 - Purchases home at 8213 W. Summerdale in unincorporated Norwood Park
1972 - Gacy murders his first victim, Timothy McCoy of Michigan, after picking him up at a bus terminal in Chicago. Gacy buries McCoy in concrete in the crawl space under his home.
1975-1978 - Gacy murders 32 more young men
1978 - Des Plaines police, investigating the disappearance of 15-year-old Robert Piest from a local pharmacy, search Gacy's home and ultimately charge him with murder
1978 - The Cook County Sheriff's Office takes control of the crime scene at Gacy's home. Over the next 8 years, 29 bodies are ultimately found under and around his home. Four others are found in the Des Plaines River, where Gacy began dumping bodies after running out of space at his home.
1979 - Of 33 victims, only 25 are positively identified. At the time, dental records are primary tool used for identification. Jaw bones of 8 unidentified victims are separated from the bodies and preserved in containers, stored with the Cook County Medical Examiner's Office. The rest of the remains of those 8 are buried in area cemeteries.
1980 - Gacy stands trial and is convicted of 33 counts of murder.
1994 - Executed at Stateville Correctional Center.
2009 - Unknown to investigators, the Cook County Medical Examiner removes the 8 jaw bones from the morgue and buries them, along with other unknown and unknown indigent people, in an unmarked grave in a hill at Homewood Memorial Gardens.