It's "Grace Brown and Chester Gillette" [Laws F7] (See The Traditional Ballad Index: Grace Brown and Chester Gillette). THE BALLAD OF GRACE BROWN AND CHESTER GILLETTE is in the DT. The title in Olive Woolley Burt's American Murder Ballads (Oxford UP, 1958, pp. 32-34; with music) is "The Murder of Grace Brown."

~Masato