Adopted a dog out, she didn't pay/collect papers, now she's saying she's been bitten and cops came to my house..

I'll try make this as brief as possible. I adopted a dog. He was lovely but chased my cats. He was freshly neutered and had swelling. The first day I had him, when I tried to check his stitches, he growled at me so I was a bit nervous. I emailed the shelter I got him from and they gave me some tips. The next day the swelling went down and he allowed me to check his stitches, rub his belly, groom him all over and we had no problems with him after that except for the harassment of my cats. After a short while, with my cats refusing to eat/come out of hiding, we decided we needed to find him a home without cats (my cats are expensive breeds and weren't going anywhere). The shelter had told me that if I rehomed him I should charge a fee so that he wasn't taken as a bait dog.

A girl agreed to take him but kept flaking on us. Eventually she said she could come but didn't have the rehoming fee, but could give it to us after the weekend. She came and I told her I'd give her all of his papers/transfer his chip to her etc. when she brought the fee. She left happily with the dog.

The next day she sent pictures of the dog with her dog and said they were doing great. Fast forward a few days and she starts bombarding me with texts about the dog peeing/pooping in her house, saying I lied about him being house trained (he never peed or pooped in our house, I didn't lie). I offered suggestions every time. Eventually she sent a text saying "He's growling at my dog and bit me." which seemed very odd because he LOVES other dogs and I feel like he would have never bitten anyone unless really provoked (if at all). She told us she was getting rid of him and she wasn't paying the rehoming fee, but we were away for the weekend so there wasn't much we could do. I was very upset.

We heard nothing from her for 4 days, then suddenly animal control come knocking at my door today. They tell me a girl (with her name) FOUND my dog, it bit her and she had asked them to come pick it up. She said it wasn't her dog, she didn't know where it came from and that she'd tried to get another shelter to take it but they were full.

Animal control looked through all my texts and emails which prove she in fact adopted the dog over a week ago, and first told me she wanted the dog two weeks ago. Should I be worried? I'm so so so upset about what is happening to this dog, he is a wonderful dog and I'm scared he will be put down, but am I at all responsible here? Even the animal control officer said it seemed like she had got mad at the dog peeing in her house, hit the dog and the dog had bitten her in response. She was as pissed off as I was about this and was incredibly helpful, but now I'm just so nervous..