By Hendrik Sackmann
STUTTGART, Germany (Reuters) - A former member of the far-left Baader-Meinhof gang broke almost 20 months of silence at her murder trial on Monday to deny involvement in the assassination of Germany's chief prosecutor in 1977.
Authorities had been hoping that Verena Becker's trial would answer one of the last remaining questions about an anti-establishment guerrilla campaign that rocked West Germany in the 1970s and 1980s.
Although three members of the gang, also known as the Red Army Faction (RAF), were convicted of the killing of Federal Prosecutor Siegfried Buback at the height of the campaign, their vow of silence meant that the identity of the motorcycle rider who shot him in his car was never established.
Buback's son Michael has joined the case as a civil plaintiff in the hope of finding some closure.
But the 59-year-old, being tried in the courtroom built specially to try RAF members at the Stammheim high-security prison in Stuttgart, broke her silence only to assert her own innocence, not to incriminate anyone else.
"I cannot answer the question of who killed your father. I wasn't there," she said in a 20-minute statement, delivered in a trembling voice. She said she had been in Yemen at the time of the killing.
Prosecutors say they have no evidence to suggest that Becker herself fired the shots, but she went on trial in September 2010 for complicity in the murder after her DNA was found on letters in which the RAF claimed responsibility for the assassination.
A long list of former RAF members summoned as witnesses have all asserted their ignorance or their right not to testify.
Becker herself served 12 years in jail for membership of the RAF, having been captured with the murder weapon in her car.
She was pardoned in 1989 and began a new life under an assumed identity.
The RAF, co-founded by Andreas Baader and Ulrike Meinhof, emerged from the student protest and anti-Vietnam war movements in West Germany in the 1960s.
They tapped into a vein of resentment at the failures of a cumbersome de-Nazification process and anger at a generation who had lived through the Nazi era and gone on to live comfortable, capitalist middle-class lives.
The gang are believed to have murdered 34 people between 1970 and 1991, mainly senior establishment figures but also chauffeurs and bodyguards.
(Writing by Alice Baghdjian; Editing by Kevin Liffey)