premise: The Oakland County Child Killer (OCCK) is an unidentified serial killer responsible for the murders of four or more children, two girls and two boys, in Oakland County, Michigan, United States in 1976 and 1977. Several theories and suspects have been named in the case, but despite all these theories, the cases remain unsolved and the killer(s) have never been identified.
hypothesis: There was more than one person involved in the OCCK murders.
reason: They are not sure whether or not there is more than one murderer. I think the system may have counted the victims as "involved" in the murder.