Those of you who faithfully--or even agnostically--read this blog probably recall me linking to Cryptomundo on occasion. The blogger there, Loren Coleman, is a foremost authority on one of my sub-hobbies, cryptozoology. What you may not know is that Mr. Coleman has published a book (at least one that I know of) and has another blog on an entirely different matter.
The Copycat Effect keeps track of exactly what it says: the copycat effect in serial killings and mass murder. His observations on the most recent school shooting in Cleveland is here.