Since all that was taken was two dollars, I would bet it was kids.....That is so sad, not just for your son, but for our society.
I remember when our DS got his first car. It was just an old rattletrap, what he could afford. He started working full time the summer he turned 16, saving for a car. He had it less then a week when it was stolen. He got it back, but it really broke his heart.
Times have sure changed.... :-(