Someone killed at least four children in Oakland County, Mich. between 1976 and 1977.
Investigators have been working for decades to determine who the serial killer is and if he is still alive. Those who knew the victims -- their families, friends, classmates, teachers, coaches and neighbors -- have been forever changed by what happened during the 13-month period from February 1976 to March 1977.
In that time, the four children were abducted and murdered with their bodies left in various locations within or just outside Oakland County.
The murders shocked communities around Southeast Michigan. Families started taking precautions, like prohibiting their children from leaving the house.
"Every mother walked her child to school. And at the end of the day, every mother would pick them up," said L. Brooks Patterson, who was the Oakland County prosector at the time. "Parents would not let their children out of their sight."
The crimes, which started in 1976, launched an all-out manhunt for what police would eventually call the "Oakland County Child Killer."
Watch Chapter Two of Child Killer: Out in the Cold in the video player above.