NEW EPISODE

FRIDAY, SEPT. 8

9:01-11:00 p.m. - 20/20

Long Island Serial killer: "20/20" investigates the shocking Gilgo Beach murders.

'20/20' INVESTIGATES THE DECADELONG SEARCH FOR THE LONG ISLAND SERIAL KILLER

All-New Two-Hour Program Features Exclusive Interviews With Boyfriend of Missing Woman, Close Friend of Victim, and Investigators Who Identified Rex Heuermann as the Lead Suspect in Three Cases

'20/20' Airs Friday, Sept. 8 (9:01-11:00 p.m. EDT), on ABC, Next Day on Hulu

When 23-year-old Shannan Gilbert disappeared in May 2010, the search led police to Gilgo Beach, Long Island, where they found human remains - not of Gilbert, but of four other missing women who had been working as escorts: Melissa Barthelemy, Maureen Brainard-Barnes, Megan Waterman and Amber Costello. Eventually, authorities discovered six other bodies along Ocean Parkway. In an all-new episode, "20/20" contributing anchor Deborah Roberts reports on the dramatic twists and turns in the more than decadelong investigation to find the killer or killers - ranging from a federal investigation into a police chief to the latest forensic technology - until, according to authorities, the latest DNA technology resulted in the arrest of architect, family man and Long Island resident Rex Heuermann. He has been charged with murder in the deaths of Barthelemy, Waterman and Costello, and has pleaded not guilty just this year.

The all-new two-hour program features exclusive interviews with Alex Diaz, Gilbert's boyfriend, who sheds light on the aftermath of her disappearance; Sara Karnes, one of the last people to see victim Brainard-Barnes alive and who received a taunting phone call after her disappearance; and former Suffolk County law enforcement officers Stuart Cameron, Timothy Sini and Geraldine Hart, who provide critical insight into the investigation and how they found the suspect. The episode also includes additional interviews with family members of the victims; key players in the case such as Suffolk County Police Commissioner Rodney Harrison and Suffolk County Defense Attorney Ray Tierney; the Gilbert family attorney; and more. "20/20" airs Friday, Sept. 8 (9:01-11:00 p.m. EDT), on ABC, next day on Hulu.