Help. Dont know who to call or what to do

We have a cat lady across the street and she has over time gotten more and more cats because people know she’s THE cat lady and they dump their unwanted cats on her property. She lets them hang out in her garage. We’ll this past month a couple rented out the house next to the cat lady. They are now poisoning the cats, torturing, and shooting them with a BB gun from their window. Even shooting the cats that are on HER property. They have a cat trapped in their attic starving it and at night the cat lady can hear it crying. She has already called the cops multiple times. They show up then leave minutes later. Tonight we came home and there was a cat dragging its back legs. The cat lady was going to take it to the emergency room probably to put it down.

What else can be done? This is fucked up and im tired of doing nothing. Part of me wants to vandalize their stuff but they can easily do the same right back. And im trying to do the right thing here but the police dont seem to care !!