The short story of it is the title and there is a TL;DR at the bottom. I'm located in Minnesota, USA

My brother, Andrew (24M), bought a puppy from our father whose a dog breeder, Jason around 2019. In this time he's beaten her for being in heat and bleeding on his bed, dehydrated her to the point where she had to go to the vet, neglected her, doesn't take her outside, etc. He's ALSO thrown cats against the wall, kicked the cats, tried to drown the cats, burned their whiskers, held a cat by it's front paws over a 10 foot drop from a balcony, and otherwise taunted and tormented them. He moved out around 18-19 but after getting out of jail in March he moved back in with my mom (Anne). I am 19 and also live with my mom. He was initially charged with criminal drug possession, child neglect, and animal neglect As he was growing shrooms in his small apartment with his girlfriend, kid, and dog. He also hasn't taken care of this dog ONCE in the sevenish months he's been here. My mom pays for her vet bills, food, etc. We feed her, let her out, give her water, walk her, play with her, etc.

None of this I can prove, but the dehydration vet visit could be proven by looking at bills if Jason still has them and I filed a police report for trying to drown my cat. Nothing came of it since I didn't have any proof like pictures or videos, but a report was still made.

However, Last night (1 am) he got drunk and bored and decided to sick his dog Luna on the cats for fun. 1 cat got away and crawled into the ceiling from the laundry room, but still has noticeable saliva and dried fur on him. The other cat, Otis, was in the basement and faced the brunt of it as he couldn't get away so easily. He got lucky however and nothing was broken and there was no internal bleeding. There is a dog bite mark on his face and his third eyelid had a cut, but that's it. My grandma heard the commotion and went downstairs to stop it. We all live upstairs, he lives in the basement because there isn't a room for him.

I have videos of the blood and broken glass and cat poop all over the basement, I have videos and pictures of the cats, their wounds, and the dried fur, etc. There's a vet receipt, etc.

If my mom doesn't file charges against him I will, but the question is, What can I do? I didn't catch him in the act but I have evidence of the aftermath. And It wasn't him specifically, it was his dog, but he trained the dog to do that, and kept making the dog attack the cats. And he feels no remorse at all. His response: "She (the dog) needs to put the cats in their place".

But I'm also worried about Luna. She is such a friendly dog towards people and has only attacked the cats when given this command, otherwise she's completely fine with them. All of us in the house want to keep her, (I'd do some serious retraining and conditioning to try and train this command out of her, as well as muzzle training). Because he seriously neglects this dog and I fear for her safety. Plus he may have to live in his car if he doesn't find a place to live, because he's getting kicked out today.

Jason still has her AKC paperwork and doesn't think Andrew ever registered, so I plan to meet up with him and register her myself, that paired with the records of my mom paying vet bills and food, could we claim ownership? Thank you in advance.

TL;DR: What charges could be filed against my brother, Andrew, for training his dog to attack my cats, and making her keep attacking them, especially if one had to go to the vet? Secondly, My mom has records of vet visits and bills being paid, under her name, and If Andrew hasn't registered her paperwork with the AKC (None of us think he has, and Jason, our dad still has the paperwork), could I register her under me and claim her as my dog so we can still keep her? Thank you in advance.