My ear has "gone." I just listened to Ralph Stanley explain the song. It is a true story, and the song was written by the prisoner, according to Stanley. The man shot the High Sheriff of Buchanan County (pronounced Buck'-anan). He was from Dickenson County.
The sound is a little clearer on this superb program, which explains Stanley's background and that of the Old Regular Baptist Church. The small Baptist church to which Stanley belonged sang much the same way as the Old Regulars, who preserve an 18th C. style. Stanley
Buchanan Co. is in the little triangle of VA that sticks up between Kentucky and West Virginia. Dickenson Co. is just to the southwest.