Mark Collman was reported missing by his parents on April 3, 1979, after his boss called to report that he did not show up for work. Mark was living in his parents' basement and working at a Model Box factory in Illinois. He has not been seen or heard from since that day.

Mark's family stated that he was close with his younger brothers and would not have gone so long without contacting them. His parents had him declared legally dead after his disappearance and erected a gravestone for him. However, little information is available about Mark's case, and the circumstances of his disappearance remain unclear.

Foul play is considered a possibility, but there are no leads in the investigation. The case remains unsolved, and authorities continue to investigate any new information that may arise.