I don't even know what to say in cases like this. A horrible tragedy all the way around. The loss of a beautiful precious child to a mother who, at least from everything in your story indicates, was in the middle of a psychotic episode. In spite of the media coverage when they happen, these kinds of murders are rare.

But certain symptoms - hearing command auditory hallucinations (for example, hearing the voice of "God" who tells you that, like Abraham, he is testing your devotion to him by commanding you to sacrifice your child) or having paranoid delusions (your loved one has been taken over or possessed by the devil) do increase the risk. I wish so much that someone could have intervened before this happened.