So sorry for you loss and all that you are having to endure!
My heart aches for you.
Try not to be mad at the dog. He is just doing what he was trained to do.
Maybe your brother would consider rehoming him???. Does he live near you? Will your daughter be exposed to the dog all the time?
You should definately report this to the police and let them make recommendatons. Especially if this dog is a danger to other.