I had a case with facts like this. My client's cat was baited and trapped, taken to the shelter. The shelter was told by the defendant that the cat was feral, and the cat was euthanized. The shelter now has new rules about accepting cats, and holding cats for a minimum period, unless they are so injured that the only humane thing to do is euthanize them. It was a really sad case, and my client was heartbroken at the loss of her cat.
I would strongly recommend that you contact your County's shelter, tell them what is happening, and be prepared to provide them with some evidence. They are going to need more than your word to investigate. Pictures or video would really, really help.
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I agree with the other two attorneys, and you should also report this activity to Animal Control. One caveat though, in many jurisdictions, a person is allowed to shoot feral animals that come on his property. If this is one of those places, then they might not take action since he is bringing them in alive and he doesn't even have to do that. The key is proving the trap is baited. That might be against a city or county ordinance.
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