Oh, how horrible - a poisoned cat and an impaled cat!

Now - call the PD and obtain the numeric identifier of your case and the last name of that nice young officer who came over.

Write down everything that has ever happened, send to the police department (in my city, Animal Control is part of the PD, so no need to send to different places, but check with your PD). Reference the case identifier, list the officer's last name, and send it to the PD, asking to add to the case. Then if there are more incidents, you will have prepared a case.

ETA: ask the neighbors if they are willing to add their reports.

I assume the PD themselves may know how to route it to social services for senior citizens. I think Lizardlady is right - since this is not new, she is just mean and vile. Of course, she can be both mean/vile in general and demented "to boot" .