Although I am not very deeply in Italian folksongs, there are some interesting murder ballads (if you think you can manage Italian). One of the most famous is "Donna Lombarda" (Woman from Lombardy) about a woman who tries to poison her husband in order to be free to stay with her lover, but the husband finds out that the wine is poisoned and so he forces the wife to drink it herself. In another one, the woman suffers for the loss of her beloved so she keeps his head buried inside a vase of flowers. Than we have Santa Lucia (Saint Lucy) who wants to keep her maidenhead; and when the King of France kidnaps her in order to force her to marriage, saying that he is in love with her eyes, she takes her own eyes off and gives them to him. And so on...
Luigi