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 remains unsolved. Della Sala's death, which remains undisclosed, is one of the oldest cold cases ever solved and the earliest confirmed murder by Cottingham. In addition to the new confession, the series includes interviews with Anzilotti, never-before-heard audio recordings of the conversations, intimate exclusive footage, and multiple confessions from Cottingham.