The original artist is dead, and so probably won't be filing a suit, though I suppose his heirs might.
The guy who bought the piece from Ward Churchill would seem to have grounds for a suit, for having been sold a fraudulent piece of 'original' signed artwork.
If you haven't been through the entire thread, we found another fraud at post #187.
http://www.freerepublic.com/focus/news/1350713/posts?page=200#187