Someone Stole Dred, Son's New Puppy

I'm mad. I live in a newly built neighborhood. Most people around have dogs. My wife has a Shtizu, and I recently bought my son a chocolate lab. And someone had the never to come in my yard and steal him. This isn't the first time someone had the never to come into my yard and get my son's puppy.
I sometimes kept the garage door up and let the dogs play in there. The puppy I keep on a leash, that is long enough for him to do his thing on the grass and still have shade and shelter in the garage. Well, I heard the dogs barking a lot, I went to see what was going on, and these kids from the other side of the neighborhood, had taken the puppy off the leash, and he was chasing them. I told them to leave and never come back. Well, that same night I went to bring the dogs in and Dred (puppy) was missing. The next morning I went directly to the kids home, and they had Dred.
Friday, I went to work, and my wife let the dogs out to play and use the restroom. By the time she went to check on them. Dred was gone. We I return from work, I went directly to the kids home, and the claim they haven't seen Dred.
My other neighbors have dogs, and one stated their family member was looking for a dog just like the one my son has. I went to that ones house, and they claim not to have seen Dred. I got information about another set of neighbors, who were accused of stealing dogs and selling them. I went to them, and they claim not to have seen my son's dog.
I need to know what to do, because I am sure one of the three has my son's dog, and by now he is far far away from this neighborhood. And without any evidence how can I prove one of these three sets of people stole Dred.