The same way that the Unabomber's brother stopped the Unabomber from blowing up any more victims. Pick up the phone, call the Police and report the crime.
This ought to seriously bother you. Why doesn't it?
You are kidding aren't you. I once actually tried that long long ago. Fortunately a very kind and understanding police officer very politely informed me what was about to happen to ME if I actually filed that report. This little old lady is just "lucky" she hasn't been hauled off Elian style by some jack-booted thugs.