Civil Matter Advice

So I purchased a bird from the Los Angeles Callejones. I had him for about a week when my sister called me and told me about a post she saw in a group from the city we’re from about a bird that had been stolen from outside someone’s home. She said the bird looked just like the one I bought.
I told her I didn’t think so since I had purchased him in Los Angeles, about an hour away from where he was stolen. Out of curiosity, I called the number on the post and asked if they wanted to come by my home to see if he was the same bird they were looking for. The woman asked if I could send her a picture, so I did. She immediately called me back crying, saying, “It’s him, it’s him.”
She asked if I could bring him to her or if she could come pick him up. I told her she’d have to pick him up because I don’t drive and usually get rides from my family. I gave them my address, and they arrived about an hour later. I invited them inside because the bird still hadn’t adjusted and would bite me, but he absolutely loved my daughter. We talked for a bit, and I told them how I had lost my own bird a year ago, so I knew exactly how they felt.
The woman’s father told me he would pay me back the $3,500 I had paid for the bird. There was also a $5,000 reward being offered, but I never wanted the reward. I only wanted to be reimbursed for what I had paid.
It’s now been a week, and they’ve completely ghosted me. They won’t answer my calls or messages. I spoke to the detective handling the case, and he told me the owners said I didn’t want the reward. That was never the issue. I wasn’t after the reward money—I just wanted my $3,500 back. It’s not fair that they got their bird back, which I gladly returned, and I’m the one left out the money after buying him in good faith. What do I do in this situation? Is there any way I can get my money back.
(Also I had no knowledge of it being a stolen bird when purchasing)

Location: California