In 1966 Stanworth was sentenced to death for the brutal kidnapping, rape and murder of two 15-year-old Pinole teens, Caree Collison and Susan Box. Their family members are still haunted by the crime.
"He had them strip and Caree ran and he yelled at her if you don't come back, I'm going to kill your friend. She came back and he shot her in the head," a family member said.
Stanworth sat on San Quentin's death row for seven years. Then everything changed.
"The first step was when the California Supreme Court and U.S. Supreme Court determined that the death penalty was unconstitutional," Uncommon Law's Keith Whattley said.
That meant, by the mid-1970s, 174 death row inmates had their sentences reduced to life in prison. At the time, California did not have life without parole, so all were eligible for release.
Besides Stanworth, the group included Charles Manson and Sirhan Sirhan, who murdered Robert Kennedy in 1968. Manson and Sirhan were not released, but Stanworth and 50 others were eventually set free.
Among them was Robert Massie, who was convicted of murder in 1965 and sentenced to death. In 1978 he was paroled; eight months later, he murdered a San Francisco liquor store owner. In 2001, after the death penalty was reinstated, Massie was executed.
"Even if they're rehabilitated, they've already done something that can't be undone," Parents of Murdered Children spokesperson misty Foster said. "Those people are never coming back, so how do say their life is only worth 20 or 25 years?"
Stanworth was released in 1990. The parole board cited his good behavior and "excellent work record." Stanworth settled in Vallejo, re-married and lived a quiet life in a gated golf course community where some neighbors even knew of his past.
"I figured he had paid for his mistakes according to the law," neighbor Irving Vanderberg said.
But on Jan. 11, Vallejo police arrested Stanworth for killing his 90-year-old mother Nellie Stanworth at his home.
While the Stanworth case and a handful of others are certainly troubling, they are also the exception when it comes to death row inmates and convicted murderers who've been granted parole.
"I think it's hard for the public to grasp this," UC Berkeley Death Penalty Clinic Director Elisabth Semel said. "People who've been convicted of murder have a better rate of success, that is a lower recidivism rate, than individuals who commit other types of crimes."
A 2011 Stanford study found the recidivism rate for paroled murderers is less than 1 percent, much lower than the 49 percent rate for California parolees.
Keith Wattley is an Oakland attorney who represents lifers in prison, many of them murderers. He says several factors contribute to their success if they are released, much of it based on what they do, while behind bars.
"Decades of self-help and therapy programs, dealing with addictions and alcoholism from the past and finding support going forward," he said.
According to the California Department of Corrections, of the 107 death row inmates in Stanworth's "class of '72," 42 were paroled. Twelve of them committed new felonies.
Some worry the exceptions, like Stanworth's case, will prompt lawmakers to overreact by passing new laws to keep prisoners behind bars a lot longer. But those who've been touched by the violence of men like Stanworth say a sentence is a sentence.
"I know they don't have a lot of rooms there for them, but when they're that bad, put them in a 6 by 10 foot cage and forget about them; they're animals," Caree Collison's family member said.
Stanworth is awaiting trial for the murder of his mother. If convicted, he could receive the death penalty.