Former radicals held over 1975 murder

Prosecutors in California dredged up a long-dormant chapter in the annals of 1970s political radicalism when they vowed to put away four former members of the Symbionese Liberation Army, the group that kidnapped the heiress Patty Hearst, for a 27-year-old unsolved murder.

The four – Sara Jane Olson, Bill and Emily Harris, and Mike Bortin – were arrested at a variety of locations on the West Coast on Wednesday and charged with involvement in the killing of Myrna Opsahl, a disabled 42-year-old woman shot dead during an SLA bank robbery near Sacramento in 1975.

For years, the case was deemed to be impossible to prosecute for lack of evidence. The bank robbers were all hooded and the only person able to testify about their identities was Ms Hearst, the kidnapped newspaper heiress-turned-SLA activist, whose account was twice rejected by grand juries as insufficient and very possibly unreliable.

The prosecutors, however, appear to be on a roll with the arrest of Ms Olson three years ago after almost a quarter of a century on the run. She recently pleaded guilty to involvement in a plot to blow up police cars in Los Angeles and is due to be sentenced today.

The assumption was that the authorities had given up on the Opsahl case. That changed, however, when Mrs Opsahl's son Jon launched a vigorous campaign to reopen the investigation because of the Olson arrest. The very notion of reopening the old files also received an indirect boost in the aftermath of 11 September and President Bush's call to crack down on terrorism in all forms.

The prosecution claims it has new evidence backing up the account laid down by Ms Hearst in her autobiography, which argued that Emily Harris pulled the trigger on Mrs Opsahl and that the others were complicit in the crime because they participated in the robbery. Ms Hearst, who drove the getaway car, is immune from prosecution thanks to a presidential pardon issued by Bill Clinton on his final day in office last year.

The defendants have long claimed that Ms Hearst rewrote history to suit her purposes. Ms Olson denies she was in Sacramento that day, or indeed that she was ever an SLA member. The Harrises and Mr Bortin have already served long sentences for other SLA-related crimes.

After the arrests, Mr Opsahl said: "Our family has waited for 26 years. It's about time."