"I knew, I knew something was going to happen; he's such an evil man," a relative of Caree Collison said.
Collison was one of the two teenage girls kidnapped, sexually assaulted and murdered by Dennis Stanworth in 1966.
"He had a gun on him and he had them strip and Carree ran and yelled at her if you run I'm going to kill your friend," the relative said. "Anyway, she came back and he shot her in the head."
On Wednesday, Vallejo police say the 70-year-old Stanworth called to say he murdered his mother Nellie Stanworth at his home in the Hiddenbrooke Golf Community.
"We obtained a search warrant, searched the house thoroughly and found evidence of that crime contained within the house," Vallejo Police Lt. Jim O'Connell said.
Vallejo police say they have been aware of Stanworth's presence in their city for about 10 years because he had to register with them as a sex offender when he moved there and had to check in once each year,
Nellie Stanworth had been living in an American Canyon mobile home park. Neighbors say they hadn't seen her for a month, but her son was a regular visitor.
"I have no idea why anybody would want to do that to her, let alone her son," neighbor Phillip Bensing said.
Irving Vanderberg lives across from where Dennis Stanworth lived for the past decade.
"I had no fear of him," he said.
Stanworth has a violent criminal history, including a kidnapping and rape in Richmond in August 1965, a kidnapping and rape in El Sobrante in November 1965, a kidnapping and rape in Richmond in May 1966, the kidnapping, rape and murder of the two teens from Pinole in August 1966 and two days later, a kidnapping and rape in Pacifica.
After his conviction, Stanworth made statements saying, "The fact is I did it and I am guilty as charged and there is no doubt to that fact," and "I had a fair and impartial trial and swear that the conviction, which has resulted in the sentence of death is valid."
Stanworth was initially sentenced to death, but in the 1970s California's death sentence was overturned and his sentence was reduced to life in prison and then, he was granted parole in 1990.
The family of Caree Collison was well aware he had moved to Vallejo. They even circulated flyers to neighbors near the killer's home to make sure they knew of his violent past.
The relative says after they distributed the flyers they received a call from Stanworth's parole agent telling them they were harassing him.