One thing you need to be aware of when starting to research John Ringo is the role author Glenn Boyer played in spreading a fictional account of the death of Ringo. However, he presented it as historical fact based on a manuscript he attributed to Wyatt Earp's wife, Josephine, when in reality it was a total fabrication written by Glenn himself.
This article by Gary Roberts is one of the best you can read to begin to understand the "dark side" of research into the Cochise County Earp-Cowboy War. It is from the Tombstone History Archives at the top of the page, already referenced to you by Eddie Lanham.
http://www.tombstonehistoryarchives.com/the-real-tombstone-travesty.html