Gary Ridgway was a killer.
Gary Ridgway . He was initially convicted of 48 separate murders and later confessed to nearly twice that number . As part of his plea bargain , an additional conviction was added , bringing the total number of convictions to 49 , making him the most prolific American serial killer in history according to confirmed murders . He murdered numerous women and girls in Washington State during the 1980s and 1990s .