(sorry in advance for the long read..)

I live with my fiancé in our own apartment currently, but last year we were living with his dad and his dad’s wife. A little over a year ago today they got a new puppy, after one of the three rescue dogs they previously had died. The puppy is/was SOO STINKING CUTE. No one is sure of the exact breed or mix of breeds but she is a truly gorgeous dog. While we were living with them I was a witness to what I feel was both animal abuse and neglect, towards the puppy. The other two dogs of theirs are treated pretty well and I have never seen any direct abuse towards either of them, JUST the puppy. It started with little things like shouting at and spanking the puppy when it would pee inside, but it got worse to the point where they were practically beating the dog and would then throw and lock it outside w no food or water for hours (they thought) on end if she had an accident inside. Their abuse seemed to progressively get worse towards that specific dog. I would cry and beg them not to treat the dog that way and try to reason with them but they wouldn’t listen. I would always sneak outside to give her food and water (she never went without for more than 30 mins while i was there bc of this) and lots of pets ofc. While I was still living there, a neighbor had anonymously called animal control and reported them but when they came to investigate, my then bf’s dad and his wife explained it all away and animal control APOLOGIZED TO THEM for all the trouble! I was not home at the time they came, or I would have told them I had been a witness to abuse and neglect right then and there. Like I said my fiancé and I now live in our own apartment and have the max 2 pets allowed in our complex so we cannot take in any more animals, but my fiancé told me his dad had mentioned to him they are now trying to get rod of their dog, and if no one takes her he’ll either release her out in the desert or shoot her.. BOTH OF WHICH ARE OBVIOUSLY NOT OPTIONS I AM OKAY WITH IN THE SLIGHTEST.. the whole situation is so heartbreaking to me, I have never been witness to someone’s total disregard for an animal’s safety or happiness like this before and I just don’t know what to do. I want to call Animal Control on them again, but I’m worried like last time they won’t be able to do or find anything as there isn’t really any “proof” of abuse or neglect. I would take the dog myself if we were able to have another (i already asked our complex to make an exception or to let us end our lease early) and i cannot find any friends or family willing to take in a large dog.. any advice on something I can do would be extremely appreciated. i just feel so helpless and so so sorry for the puppy we left behind with them. please any help or suggestions on something i could do would be very appreciated. please keep the negativity to a minimum, i agree they are HORRIBLE people, but i just want to focus on finding help for the pup.