Four former members of the radical Symbionese Liberation Army (SLA) have been sent to prison for between six to eight years after being found guilty of the murder of a bank customer during a hold-up in 1975.
The four apologised to Opsahl's relatives for her death William Harris, his ex-wife Emily Montague, Michael Bortin and Sara Jane Olson had admitted second-degree murder in a California court in a plea-bargain that prevented a possible life sentence.
Montague - who had pulled the trigger which fired the fatal shots in the robbery - received the stiffest sentence of eight years, while Harris received seven years.
Olson - who is already serving 14 years for an attempt to blow up two police cars in 1975 - received six years, as did Bortin.
The four were notorious as members of the extremist SLA, a group responsible for committing some of America's most infamous crimes in the mid-1970s, including the kidnapping, and subsequent brainwashing, of heiress Patty Hearst.
Hearst, who was present at the robbery, was at one point thought to be a possible witness in the four's trial, but the plea deal meant this never transpired.
In court all apologised to relatives of the victim - Myrna Opsahl, a 42-year-old housewife shot as she deposited church money at the Crocker National Bank in Sacramento.
"I've thought about your mother a lot," he told Opsahl's son, who was present at the sentencing.
"Your mother was never an abstraction to me. It's absolutely unacceptable that this happened."
"I will be sorry for the rest of my life," added Montague, who had admitted in an earlier court hearing that she had levelled a sawn-off shotgun at Mrs Opsahl, but claimed it had gone off accidentally.
After a dramatic showdown with police which left most of its members dead the remaining SLA members fled, many turning to a life in quiet American suburbia.
Olson was finally captured after more than two decades on the run in 1999 in St Paul, Minnesota, where she had been living under an assumed name as a doctor's wife, community theatre actress and mother of three.
The others were picked up by police soon afterwards.
The last remaining SLA member, James Kilgore, was captured in South Africa last year, where he had been working as a university professor with a wife and children.
He was extradited to the US last month, and is expected to plead guilty to forgery and federal explosives charges in court later this month, Reuters news agency reported.