Premise: Gary Leon Ridgway ( born February 18 , 1949 ) is an American serial killer known as the Green River Killer . 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 .
Hypothesis: Gary Ridgway is a serial killer.
Label: ENTAILMENT