Gary Ridgway is an American serial killer who was active in the late 20th century. He was convicted of 49 murders in Washington State, making him the most prolific serial killer in United States history. He was arrested in 2001 and is currently serving a life sentence without the possibility of parole
From Wikipedia
Gary Leon Ridgway, known as the Green River Killer or the Green River Strangler, is an American serial killer who was convicted of murdering forty-nine women between 1982 and 1998 in the northwestern United States. At the time of his arrest in 2001, he was believed to be the most prolific serial killer in United States history, according to confirmed murders.