According to Bert Lloyd somewhere in the writings of Daniel Defoe (never been able to find it) there is a description of balladmakers visiting condemned men in the prisons and taking down details of their crimes (last confessions), then making ballads of them to be sold at the (public) hangings. They were referred to as 'goodnight ballads' because of the practice of the crowds at the hangings of shouting "goodnight" as the noose tightened around the prisoners neck.
Two books worth seeking our (though probably long out-of-print).
Bloody Versicles - The Rhymes of Crime by Johnathan Goodman (David and Charles 1971)
and the somewhat odd but interesting:
The Newgate Garland, W.L.Hanchant (Desmond Harmsworth 1932)
Jim Carroll