The link provided by Charlie Baum offers a lot of good information.

There's virtually no similarity between "Frankie and Johnny/ Albert" and "Frankie Silvers." (Follow the links at the top of the page to the "Silvers" texts in DT.)

Sandburg's reference to "Frankie and Johnny/ Albert" being sung in 1888 is almost certainly mistaken. The various versions known today are ultimately based on the 1899 murder of Al Britt in St. Louis.

The lively "Leavin' Home" version was composed in 1911-12 by the Leighton Bros., a popular vaudeville team. I've seen the sheet music.

Randolph-Legman gives a lot of information on all of this. Bruce Buckley wrote a dissertation on the whole issue of "F & J" at Indiana University back in 1962. Since then there have been no significant new discoveries about the origin of the song.