ABC News

Dean Corll, the Candyman serial killer, terrorized the Houston area by raping, torturing and murdering young boys before he was shot to death by his accomplice.

Now, 40 years later, authorities believe a filmmaker may have uncovered evidence that there was an unknown, 29th victim.

Josh Vargas, a Houston-based filmmaker, gained access to the belongings of the man who shot Corll, Elmer Wayne Henley, that the incarcerated man's mother stored in an old school bus.

"While rummaging through those pictures, this Polaroid falls out," Vargas told ABC affiliate KTRK. "I take a look at it and, right off the bat, having studied the case and the crime scene photos and everything, I see Dean's toolbox, and I see his implements in that tool box, and I see this kid right here with handcuffs on his arms."

Vargas gave the photograph to the Harris County Medical Examiner's Office, which reviewed the photograph and determined it was not of any of the known victims.

Henley, who was asked about the photograph, told the filmmaker he believed there were more victims who have not been found.

Corll, along with two accomplices, abducted, sexually assaulted and tortured young boys before killing them. He gained the nickname "Candyman" because he was known to give candy from his family's business to young boys.