I don't have a link to this story, just something that happened to a friend of mine when we both lived in Alabama. My friend has two pitbulls and are some of the nicest dogs I have met. One day, across the street, someone tried to break into a house and the alpha pitbull (Macy) jumped over my friend's fence and stopped the break in (another neighbor saw the person that broke in and called the cops). The guy was arrested. Macy simply sat in front of the entrance of the fence when my friend got home.
The cop said that it is illegal to have pitbulls in Lee County in Alabama. However, he said he will look the other way because every neighbor said these dogs are the neighborhood watch dogs. It was a nice story and thought I would pass it along.