One possible source of the gunman's reference to "Ismail Ax" on inside of his arm is... James Fenimore Cooper's The Prairie. Character Ishmael Bush had an axe. "And the axe, which created and transformed through destruction, clears the figurative way for the deflowering of the New World." The axe is apparently both literal and symbolic, and references are made about the character's having moved from the east to the west, creating change through the destruction (using the axe), and the like. Just a possibility, esp. for someone who was an English major?