The Christmas time Billy Lyons shooting involving the hat that is mentioned in most versions of the song happened in St Louis (I can see the site from my window) - assuming the Globe Democrat reported it accurately in its newspaper a couple of days after the fact. However it is clear that the story and the song soon eclipsed the facts and created in Stack a symbol of the original bad dude of the Mississippi River area with stops in Memphis, New Orleans, steam boats etc, no doubt compounded by similar names, events and people in those places. The story had the appeal of universal recognition - everyone knew a Stack and he was cool, as long as he didnt shoot you. The folk process happens to stories (even facts) as well as songs.
My only regret in reading the accounts is that Stack didnt die in the 'lectric chair with his head held up high saying "my six shooter never lied". He didnt even die while in prison for the murder conviction - but for some later offense. I debated whether to leave that verse out of my version of the song - but I figured that it is a song not a history lesson (but I ususally explain the difference after the song).
For some reason St Louis seems to revel musically in its murders - besides Stagger Lee, the Frankie/Albert, and Duncan/Brady shootings can both be placed there by various sources although those facts too are probably clouded by legend that surrounded them.