Jon Opsahl became an unlikely hero. He never forgot his mom's brutal death at the hands of one of California's most notorious terrorist gangs, the Symbionese Liberation Army (SLA), when he was 14 years old. His relentless perseverance in helping find his mother's killers eventually started police and prosecutors on a 28-year odyssey that ended with the rounding up of the vicious killers: the ringleaders of the SLA. Jon's mother, Myrna Opsahl, was 42 at the time of her death. She was killed during a robbery of the Crocker National Bank in Carmichael, near Sacramento, on April 21, 1975. Opsahl,...