My neighbor got rid of my cat?

What can i do against my neighbor who got rid of my cat?? My cat was an outdoor indoor cat, and would roam around my front and back yards.these new neighbors moved in 3 days ago, and they would try to scare my cat away, now my cat is gone. What can i do against these assholes? Foxy is my baby and now i can't find him anywhere :( I left food out and called his name but he's nowhere to be seen. He's been missing since yesterday and i dont know what to do? What can i do? He was my baby and now i feel empty without him :(