I don't care how much time has passed. All of them should rot in prison for the rest of their lives. No parole, ever.
The problem is inconsistency. It appears that if you kill somebody famous, or the crime is particularly notorious, California's parole board will bury you forever, e.g Van Houten, Krenwinkel, Sirhan Sirhan. But the average murderer in California serves something like seven years and change. The case I remember most was a grad student at one of the Universities some seven years into his Masters, who bludgeoned his advisor to death with a hand sledge. He REFUSED parole because it would have required him to stay away from the University if released. He chose to max out instead. So he did seven years and THREE MONTHS. Bet the folks at the University felt real good about their state's enlightened approach.
Van Houten and Krenwinkel have done everything one expects from a potential parolee. They got college degrees, were gainfully employed by the prison system, learning trades to do so, participated in 'Scared Straight' type programs and showed remorse for their crimes. They have served in excess of forty years in prison. California should drop the hypocricy, and publicly admit that in their case, parole is an illusion - that they will never be released. Because, in California, it appearswho you kill, not that you kill, is the determinative factor on whether or not you will ever be'eligible for parole.