The only discrepancy is the stairwell proximity. The mage came out of his room to throw the fireball, but only as far as the railing in front of the room. That is where he died. There is no need to check him, if yours or Clem's shots didn't kill him, he will bleed out soon enough, and the tag kind of faded as he did. I would also point out, any real investigation of him will mean exposing yourself to fire from the sniper.