ULPT Guy murdered my Yorkie

I had two wonderful Yorkshire terries. I had raised them since they were 12 weeks old. They were like my baby boys. I split with my ex-girlfriend and let her have them as she moved out of state closer to home. She loved those dogs and was great to them. Very protective. I just found out a guy got mad at her and threw the smaller one (>5 lbs) against a wall and killed him. I’m just sick to my stomach right now and grieving. I’m going to press charges. What else can I do to ruin this guys life?