'20/20' REPORTS ON HUNT FOR ONE OF THE MOST NOTORIOUS KILLERS IN AMERICA WHO EVADED CAPTURE FOR OVER FOUR DECADES

'20/20' Documents Story Through Lens of Bestselling Crime Author and Law Enforcement Who Tirelessly Tracked Killer

'20/20' Airs Friday, Oct. 30 (9:01-11:00 p.m. EDT), on ABC

A new "20/20" details the investigation into the dark world of one of the most notorious killers in America and one woman's relentless determination to bring him to justice. The killer terrorized idyllic California neighborhoods in the 1970s and 1980s, evading authorities as he lived among his victims for over four decades. During his attacks, he talked to his victims and once cried out about a mysterious woman named Bonnie. Was it a tantalizing clue into his motivation? ABC News' "20/20" reports on bestselling true crime author and web sleuth Michelle McNamara's obsession with solving the case before her death; and includes interviews with investigators dedicated to the case, including former cold-case investigator Paul Holes who tirelessly tracked him for 24 years, and genetic genealogist Dr. Barbara Rae-Venter who helped crack the case in 2018 using DNA, finally revealing the shocking identity of the monster behind the mask. "20/20" also has emotional, candid interviews with survivors who open up about their attacks, his capture and their lives today. The two-hour program also features rare footage of the killer, extensive archival footage and police files, and reports on the capture and his double life as a husband and father. ABC News' "20/20" airs Friday, Oct. 30 (9:01-11:00 p.m. EDT), on ABC.

"20/20" is anchored by David Muir and Amy Robach. David Sloan is senior executive producer. Muriel Pearson is senior producer; and Cari Strassberg, Jonathan Balthaser, Sunny Antrim and Kelley Robinson are producers of this episode.