A new Sweeney book will be released soon: Cochise: Firsthand Accounts of the Chiricahua Apache Chief by Edwin R. Sweeney (Apr 24, 2014) this is USA release date, In the UK it can be pre-ordered but no release date yet.
The topic is interesting. But I wonder whether there is much more that can be gleaned out of the historical data. I suspect we are at an impass, and not much that is new can really be learned. There is much that we will never fully know - it disappeared into history and is lost in time and folklore. So people will believe what they want to believe.