That was one really creepy episode.. I mean.. someone who managed to get to Gibbs and really drow him off guard and as it seems, that is not the first time.. It was great too see Ducky to worry about him.. and the whole tension that criminal and Gibbs had.. playing those game like with the sketchbook and lighter..
But the whole case.. the way they got the sketchbook.. they were trying to find the dumping ground and when they did.. they realized they have missed something important.. I thought the new kills were clever trick to get them to postpone to execution but no.. it was another part of the storyline.. quite unexpected one, to be honest..