PPretty sure Zombie is not the artist. I saw on The Dirt Floor that Zombie was the artist on the above piece. I think it was a Mel Gibson with the words crazy behind it. Can't say for sure he's not involved with the MLK work but I don't believe so.
The artist is Hugh Leeman. We were both featured in the Living Walls Conference. You can peep more on him here: http://clatl.com/culturesurfing/archives/2010/08/12/mlk-vs-old-english-a-letter-from-living-walls-artist-hugh-leeman