Child abuse

I mother scratched my sister's child with a bottle on the face and head to an extend where we took the child to the Dr my Sister's child has stitches on the face the Dr couldn't do the other one because it was on top of the vein...we went to the police station to report she only spent a night and got a free bail, how when I feel like she is a threat to my sister's child because of the things she said to a child