Start chatting it up that you are setting up a camera to catch them, even if you don't. If it's someone in your neighborhood it will quickly get around to them and they'll stop.
I had some goon that kept stealing my newspaper. I told everyone that I knew that I got up now at 6am to see the paper delivered and I was watching out the front window to see who it was that was so cheap they had to steal a paper. I never had a paper ripped off again, the neighborhood telegraph worked.