How do I verify a historical document?

[editor's note: this is continuation of my self education on historical research. If you would like to follow my entire process select Research from the labels on the left.]

I found a hitherto unused account of the Cane Creek Murders. How can I verify that what it says is true? My problem is that 1) it is a third hand, or more, account and 2) it is somewhat different from existing accounts, even to the point a naming names. And naming names is like acusing someone of murder, which may be fighting words down here in the south. So I want to be careful. My first step, I think, will be to verify the existence of the three or four people in the story. The witnesses were Rube Mathis, and Poole Talley. The source is Court Talley and the author Lesley Talley.

First stop is the Census (thanks Ardis). No luck in the 1880 Census and the 1890 is useless. So I looked in my favorite source: published genealogies. I do find a Ruben Mathis in the right place and of the right age. His mother's maiden name was Hinson (same as the leader of the mob) so it may be a plausible connection to the mob as indicated in the account. He did have one daughter and two granddaughters who married into the Talley family.
I also see a James Poole Talley in the right place and of the right age. And he is a grand uncle to a person named Court Tally who is also the right age to have been interviewed in 1974. Lesley's account said he was an "uncle", but I won't quible over minor differences. But with all the extensive published genealogy I don't see a connection from this Court Talley to Ruben Mathis. I see Court's parents and grandparents. I have not identified one set of great grandparents into which he might fit, but the lists of Ruben's children don't match. Ah, well, lack of proof does not disprove anything. Remembered genealogy is a funny thing. Recorded genealogy is iffy enough. But it does mean I have to look closer.

Oh and Lesley Talley? Though she would have been alive (attending college) when the books I have been using were published, she would have been young enough that it doesn't bother me she isn't in there. The Talley's are a big family in that part of Tennessee. Lesley never indicated how she was related to Court Talley, so it may be quite distant.

So what is my next step?