"20/20" is investigating the case of the notorious Golden State Killer, who is accused of a violent crime spree of at least 12 muders and over 50 rapes, beginning as far back as 1976. The perpetrator was finally caught after 40 years with the help of the late Michelle McNamara's obsession with his crime and years of detective work. ABC News' Whit Johnson breaks down the case. "20/20" airs Oct. 30 at 9/8c on ABC
