It's funny how the article says the police received an anonymous tip. It's obvious the father didn't call and it's unlikely the boy would have turned in his own father, which only left one suspect--the adult female, who has no biological connection to the boy. The tip wasn't so anonymous after all.
I am not even sure that the father is even guilty of the crime he is accused of. This isn't something a loving parent would do to his child. I believe the adult female was supposed to be the boy's babysitter, there was a fight between the woman and the father earlier that day, then the woman chained the boy to the bed herself after the father left for work, fled the scene of the crime, and called the police to get the father in trouble.