A serial killer known as the “Torso Killer” pleaded guilty Tuesday to murder in the deaths of two New Jersey teenagers in 1974.

Richard Cottingham, 74, is currently in state prison on a life sentence for other murders that he committed.

Cottingham admitted to killing 17-year-old Mary Ann Pryor and 16-year-old Lorraine Kelly. The teens were friends who had left home for a trip to a Paramus mall and never returned. Their bodies were found five days later in a wooded area in Montvale.

Detectives have confirmed that Cottingham killed nine women but believe the death toll is higher. He is known as the “Torso Killer” for brutally dismembering his victims by cutting off their limbs and heads.

Cottingham’s attorney says he has “serious regret” for the crimes.