CNN Correspondent Brynn Gingras dives deeply into the 13-year investigation into multiple murders of young women along Gilgo Beach and the man, Rex Heuermann, who has now been charged with these crimes. Last week, Heuermann was arrested and charged with murder in connection with the killings of three of the "Gilgo Four," a group of four women whose remains were found along a short stretch of Long Island's Gilgo Beach in 2010. He is also the prime suspect in the disappearance and killing of the fourth woman but has yet to be charged in that case. The alleged killer had been living a double life in a village a short drive from where their remains were found, prosecutors said.This episode examines the decades-long investigation with the foremost criminology experts, including former FBI Deputy Director Andrew McCabe, CNN Chief Law Enforcement and Intelligence Analyst John Miller, and author and journalist Robert Kolker (Lost Girls: An Unsolved American Mystery). Also featured are interviews with Heuermann's neighbors and local authorities, who unrivaled the mystery, including Suffolk County District Attorney Ray Tierney and Suffolk County Police Commissioner Rodney Harrison.