You may even want to deal with your son's actions,,,, specifically, burglary!
Since some posters seem to think the blame for your son's behavior (burglary and drug use) should be placed on your neighbor, I thought I'd suggest you clean your own closet before complaining about your neighbors!
It's not legal for him to tresspass or be breaking into other people's out buildings, so he can help himself to their possessions, even if those possessions happen to be narcotics. What else did he help himself to?
Any other neighbors who are enticing your son into a life of crime and drug use?
I get the feeling there's more to this story than the neighbors alleged drug involvment. Possibly they are upset with you and your little angel for his actions?