I just dont understand people

I sit here reading the story of "Baby Grace" Riley Ann Sawyer. I cant even imagine what kind of monster could do that to a child. A sweet innocent little girl. For what not saying please and thank you. I don't understand. I cant understand how anyone could harm a child. Yes we all get frustrated with out kids from time to time, but to hurt them. How can you do that? As a mother I just cant understand how you could hurt your own child, then put her in a plastic container for a month or two, then send her lifeless little body out into the ocean hoping to never see her again. I just don't get it. I am at a loss. I am so disturbed by this. Please pray for this family.