I know it’s a little late for this, but I had my dog’s ear tattooed when we had her spayed.
Vet records, rabies shot records, etc. Facebook screen caps around the time you found the dog.
I’m afraid you’re going to have to go to court. You may not get the dog back, but you can ask for the woman to either return the dog or compensate you for the money you put into it. ($20 a day for boarding, vet bills, etc)
One more thing for future reference: My husband carries a little green book and a pen with him everywhere he goes. He makes notes in it through the day. (Only at work.) He calls it his CYA (cover your @$$) book. Sure enough, he’s used it as a reference to incidents and it has gotten him out of hot water and once a false accusation.
My daughter has started using one for every day life. It’s considered a diary and will hold up on court if it’s hand-written.
I like the idea of the CYA book. Making a “note to self” on that. I guess we will go to court. We have pictures all the way back through the time that he came to live with us. The officer didn’t dispute that. He just said her claim took priority over ours. Thank you.