The geneology of the "pop" (Kington Trio) version of Tom Dooley is pretty well documented. Frank Warner collected it from Frank Proffit, who sang it to a somewhat different tune than is usually heard. Frank revised the tune a bit, and sang it frequently. It was picked up by the Folksay Trio (Bob Carey, Erik Darling, Roger Sprung), who speeded it up a bit and added the "hitch"--the syncopation caused by a pause between Tom and Dooley. The Kingston Trio got it from them, sang it essentially unchanged, and made folk/pop history.