In addition, I think that we all believe that CN knew of the impending murder by the single comment "Have fun doing big things." It stands to reason, that if DM shared his murderous visions with CN, whom he claims that he didn't care for much, then he also called onboard his very dear friend and personal assistant, MS. Conversations throughout the early part of 2012, suggest that the missions were changing into something much more sinister. There was also a message about the level of trust that was required between them. MS' raps were becoming bloody and violent. MS was hungry and excited for the next level.
I believe that DM continued to include MS in his plans, and did not exclude him from the missions that he intended to follow. In my reading of the evidence, there's nothing to suggest that MS was completely clueless about what was happening or had happened. He always acted in accordance with the murder plan.