"Early folklorists took an interest in the ballad as early as 1911, when Guy B. Johnson published the first version in the prestigious 'Journal of American Folklore'."
This quotation is attributed to Cecil Brown in the Guardian article linked above. The 1911 article in JAFL is by Howard W. Odum, not Johnson, although the versions were repeated in the jointly authored Odum and Johnson, 1925, "The Negro and His Songs."

Neither of the two versions is bawdy; they are "sung to different music," but the music is not given. No bawdy version is mentioned.

No sources, beyond a listing of the the southern states where the song was collected; the Missouri area is not included.

The song and its versions seems peculiarly disconnected from the actual event and its locale. The supposed central character, Lee Shelton, was a St. Louis pimp, but one with political connections. He was tried for the murder of Billy Lyons, posted $2000 bail, and the trial ended with a hung jury. He received 26 years in the second trial but was released after a short time. He pistol-whipped a man, was sentenced to prison, where he died in 1912. (from the Guardian article, quoting from Cecil Brown).

His victim, Billy Lyons, does not appear in the early versions printed by Odum and Odum and Johnson.
The song may have developed independently of the Shelton- Lyons event.

The song was first recorded by Fred Waring and His Pennsylvanians, 1923. Ma Rainey and her Georgia Band, 1925, was the first Black musician to use the title in "Stack O'Lee Blues," but this song is more related to "He was my man but he done me wrong" (Can be heard on redhotjazz.com/georgiajazzband.com). Evelyn Thompson recorded "Stagger Lee" in 1927 (not heard).