Too Close for comfort

Walter Neff: Know why you couldn't figure this one, Keyes? I'll tell ya. 'Cause the guy you were looking for was too close. Right across the desk from ya.
Barton Keyes: Closer than that, Walter.
Walter Neff: I love you, too. 

It was clear right from the first interactions between Neff and Keyes that they had some type of mutual respect relationship and they both seemed to look up to eachother.  Keyes was very impressed with how well of a salesman Walter was, and Walter was very impressed with Keyes vast knowledge of the agency and the skill which he harnesses "the little man inside" who would inform him when something was up.  Keyes was such an important part throughout the film that Neffs whole narration was based towards Keyes.  All in all the relationship between Keyes and Walter ultimately lead to Walters demise.  At first the tight knit relationship between Keyes and Neff blinded Keyes into never thinking that Walter had anything to do with the events that occured.  When Walter was listening to the recording of Keyes, Keyes even admits out loud that Walter could not have had anything to do with the crime because he knew walter for eleven something years and Walter would have never done anything like this, he had no intent.  As pieces of the puzzle began to fill in it became more clear that the only possible way all of this could have worked out is through Neff.  When Walter said the reason that Keyes could not figure this one out was because they were too close, Keyes responds with "Closer than that, Walter".  What Keyes means by this was that they werent just employees who happen to have their desks across from eachother, they were even close than that on a friendship, trust level.  When Keyes discovered that Walter had been the root of all problems, his entire face turned to disappointment.  It was almost as if Keyes and Walter had a father son relationship and when Keyes found out that Walter was doing all this behind his back he was crushed in the last scene.  Towards the end of the film most of the focus was on Keyes.  Walter knew Keyes was an extremely smart man and the only worry on Walters mind was constantly Keyes.  It was clear sailing after Phillis and Walter commited the murder and threw the body onto the tracks but their was always on thing on Walters mind, Keyes.  In the end Walter knew he was done, so the final thing he felt like he needed to do was inform Keyes on how he did everything.  I sort of looked at this as if Walter was sort of helping Keyes fill in the final bits of the puzzle that Keyes was confused about and unable to put together.  Even after Keyes discovered all this about Walter and even though he looked down upon him, he still had respect for him.  While Walter was lying on the ground with the gunshot wound in his shoulder keyes bent down and returned the favor of lighting Walters cigarette.