So unless a parent clearly states they are going to kill or hurt their kids, they should just be left alone?
She locked her kids up in the house, she left her kids alone for hours. She wasn't taking proper care of them.
Ofcourse the family didn't think she was going to kill them, I don't think there are a lot of cases where the family goes like 'yeah, I knew he/she was a killer, but what can you do, huh'. But they were all worried about the well being of the children. Maybe this isn't a case of we are scared she is going to hurt them, but this also isn't a case of she was the best mom ever up and untill she murdered her kids.
So when should people intervene? where should you draw the line?