I recall Parnell's trial vividly, as it was top news back in 1981, when I was a journalism student. I even wrote a term paper analyzing coverage of the case. Parnell was convicted of abducting 7-year-old Steven Stayner and keeping the boy confined for more than 7 years, until his escape in 1980.
Stayner became something of a hero for freeing Parnell’s next would-be victim, 5-year-old Timmy White. But Stayner went on to tragedy, dying in a motorcycle accident in 1989.
Stranger yet, Stayner's brother Cary Stayner went on to become a serial killer of women in Yosemite National Park; he's currently on San Quentin's Death Row.
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Anyway, back to the Parnell case. After serving his time, Parnell was paroled to Berkeley. A sickly and doddering 71-year-old, in 2004 he tried to buy a 4-year-old child from his caretaker for yet another round of child molestation. So much for the hope that old age and infirmity automatically preclude sexual reoffending.
"Kenneth Parnell's death brings to a close his long criminal history of victimizing young children," said Alameda County deputy district attorney Tim Wellman, who prosecuted Parnell in the 2004 case.
He died at the California Medical Facility at Vacaville after a long illness.
The Crime Library has a detailed case history; Wikipedia also has a biography.