Mark Helmig was a 9-year-old boy from Pekin, Illinois, who disappeared from outside his home and was later found dead on August 1, 1976. He was described as a playful child; at the time he was last seen wearing brown shorts, a white t-shirt with a red and blue emblem, and black and white shoes. Reports say he had a troubled upbringing with allegations that his father once disciplined him with a belt and on occasion left him outside without proper clothing, which the father denied.

Investigators identified a complex set of leads, including a person of interest, transient fair worker William Freight Train Guatney, who had a history of violent crimes and was suspected in several murders of young boys in multiple states. Guatney was never charged in Mark’s death and later was found unfit to stand trial for other crimes and confined to a mental health facility. The case record also cites concerns about local police handling and coordination between agencies.

Mark’s murder remains unresolved. Anyone who knew Mark, saw him on August 1, 1976, or has information about William Guatney’s whereabouts or activities around Pekin that summer is asked to come forward.