Well of course it was. The perp was born here, slaughtered here, and is a citizen. It has to be something else that compelled him to terror. Hmmmm, what could it be? Was he a member of some violent cult? Did he read any green book with directions to violence? Did he express sympathy to any people or groups that were also violent?
Whatever could be that "thing", that commonality that they share I wonder.
Hmmm...was he a boy scout? Yankees fan? Gotta be some common factor...