Through a decades long relationship with the killer, Detective Robert Anzilotti has obtained a new confession from Cottingham for the murder of Mary Ann Della Sala, whose death in January 1967 was never solved. Not shared until now, the death of Della Sala is one of the oldest cold cases ever closed and the earliest confirmed killing by Cottingham. In addition to the new confession, the series features in-depth interviews with Anzilotti, never-before-heard audio tapes of the men's conversations, intimate exclusive footage, and multiple confessions from Cottingham regarding his recent headline-making killings never heard on tape.