The song is "Po' Laaz'us" and is in the Lomax collection, Folk Songs of North America, listed as song number 303. It refers to another Lomax collection, "Folk Song USA", which offers a couple of pages of commentary, which I can attempt to bowdlerize (I think I even did that to the aforementioned word) and put into a Reader's Digest Condensed Version.
The intro compares the African-American outlaw ballads to the Anglo-American ballads, cites a few other examples (Railroad Bill, Brady, Stackerlee) but claims "Po' Laz'us" as being the "most poignant and moving and the most widely sung of the ballads." Lazarus was a worker on a levy camp, in the days when "you worked from can to can't and maybe they paid you and maybe they didn't." One evening at the mess hall he got tired of finding "meat in his greens" (worms in his salad). Then he did something for which onwe must be feeling really pissed off and had to really have some balls. He "walked the table". He stood up on the mess table and stomped everyone's plates with his muddy boots. Knowing he'd face a minimum of a whippiong for his deed, and with revolvers in either hand, he went straight for the pay window, took the money and ran.
Our story (the song) begins with the high sherrif telling the deputy to go get "Po' Laz'us".
Another interesting note is that this was oaften sung as a work song or a gang song. There are a dozen or so verses, and it is said that when on work lines when the workers (singing the song with "much affection for the hero", came to the final verse there would be a pause when all of the hammers would drop to the ground in unison, and then the finale would come;
Cap'n, did you hear about-all yo' men gonna leave you? (2x)
Nex' Pay Day, Wo, Lordy, Lord, Next Pay Day.