Police were investigating a child pornography ring on North Fox Island in 1977, just months after three Oakland County children were killed and just weeks before another child was abducted.

WATCH TONIGHT: Local 4 Oakland County Child Killer special at 10 p.m.

The pornography operation was run by a man with ties to Metro Detroit, and police were anxious to find out if he was involved in the serial killings.

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One theory in the case is that the pornography ring was part of a group of wealthy pedophiles who trafficked in child pornography and groomed underage kids.

A massive investigation led to two people: Frank Sheldon, of Grossepoint, who owned much of North Fox island, and Jerry Richards, a teacher in Port Huron who recruited young boys to fly there on field trips.

Sheldon fled the country and was never prosecuted. Richards was prosecuted for child pornography and has since died. Investigators do not believe either man is the Oakland County Child Killer, but they do believe the killer could be someone they victimized.