Your cats were probably trapped by a one of your neighbors who was tired of dealing with them. I've personally trapped 4 of the pests and took them into the Humane Society where they were euthanized because their owners did not care enough about them to even try to find them.

I'm sorry if you think that's cruel, but I and most of your neighbors think that it's pretty selfish to allow your pets to run around and kill our wildlife and defecate on our lawns and keep us up at night and make our neighborhood look trashy. As long the law is the law, I will continue to properly remove vermin that invade my property.