I would write everything you know down- just in case anyways. I would watch her, try and see if you can use anything that would point to other stuff. And about the cats- who are they registered under? your dad,mom, or you?
I believe that she poisoned my Molly cat... and my dad was the one who found her on the bathroom floor and he felt so guilty not going to the bathroom during the night when he heard my tuxedo boy Tipper crying...