Crime scene evidence is often not enough to identify suspects
Randy Gail Sperino was last seen alive on the evening of 9 November 1993, as she was getting into a pickup truck in Granite City, Illinois.
The 34-year-old's body was found hours later in a field nearby, the victim of blunt force trauma.
The identity of her killer was a mystery. DNA evidence found at the crime scene was tested against standard law enforcement databases, but no matches were found.
For three decades, investigators from the Madison County Sheriff's Office chased leads and interviewed hundreds of people as they attempted to identify the perpetrator.