According to ABC7 Chicago news partner Daily Herald, family members last heard from Harold Wayne Lovell about 33 years ago.
He told family members he was heading to Aurora for a construction job. He never returned and his family thought he had probably crossed paths with Gacy.
Instead, Lovell left home because of a battle with his stepfather.
Family members stumbled across the fact he was alive when they were getting ready to submit a DNA sample.
Earlier this month, the Cook County Sheriff's Office opened a probe into the eight remaining unidentified Gacy victims.