A few years ago Bill Domler sent me an article or pointed me at a web page (NY Times or New Yorker or some such; I lean toward NY Times) which was a LONG backgrounder on Billy the Kid. The gist was that Garret was hired by English (immigrant) farmers to help break the Irish political machine which ran the whole area, and Billy was in the employ of the machine. Or was it vice-virtue? (What a memory.) Then Garret invented the story to conceal the real reasons for the killing, and to take advantage of the Civilized World's fascination with the Wild West. I'll try to find the article. You could try too.