If they're so proud of their handiwork they should want the public to know who they are.
A good rule of thumb for life is never participate in anything you'd be ashamed for the world to know you did.
What these guys did was pretty gutless. I should hope that they are troubled by it, but I doubt it.
I wish I could remember my latin but Horace (or Ovid - can't remember which)had a great quote. Basically it translated to - "The evil doer hates the light".
Very applicable in this instance.
John 3:20.