Stories of men or women who poison their lovers are at least as old as literature and almost certainly older.
What little knowledge we have of oral tradition dates largely to the end of the 19th century, when (extremely limited) collecting of folk songs began in earnest.
It is highly speculative to suggest that we will ever be able to pin down any of these ballads to any particular time.
Man, as a species, is a natural song and story maker and probably always has been, and the sooner scholars deal with the implications of that fact, the sooner they will take on board that these songs are just as likely to have been the creations of the unlettered as they are the literate - more likely, in fact.
Jim Carroll