Karlsruhe, Germany  - The former far-left terrorist who was arrested last week at her Berlin home in connection with a 1977 drive-by assassination was a mole, according to a German documentary Wednesday.

Verena Becker, 57, who is now an alternative-medicine healer, briefed government agents three decades ago on the innermost workings of the Red Army Faction (RAF) and received a large sum of money, the newspaper Bild said, apparently quoting the film.

After 32 years, the mystery of which RAF terrorist shot dead federal prosecutor general Siegfried Buback, his driver and his bodyguard has still not been solved. Its members dead or jailed, the RAF dissolved in 1993, but its ex-members observe a vow of silence.

In a decades-old turf war, Germany's domestic intelligence agency, the BfV, has never disclosed key files about the RAF to the federal prosecutors who oversaw the fight against the Marxist extremists.

The prosecutors have said Becker's arrest was because of new evidence of her involvement in the Buback killing. Several RAF men were collectively convicted of that crime. Becker has only been convicted of a different shooting.

The film, to air late Wednesday on ARD public television in Germany, shows Winfried Ridder, a former BfV agent, saying Becker was an informer.

Egmont R Koch, a German journalist who wrote the documentary, confirmed to the German Press Agency dpa that the account in Bild was correct.

Bild said the agents met Becker five times in a Cologne apartment rented for the purpose.

She provided tip-offs enabling the arrest of two key RAF members, Brigitte Mohnhaupt and Christian Klar, detailed RAF booby traps and disclosed the names on the RAF list of people to assassinate next.

Koch said his research had convinced him Becker was not the motorcycle pillion rider who sprayed bullets at Buback on a Karlsruhe street. Becker told agents the assassin was a man, Stefan Wisniewski.

"During my work on this film, I found no evidence to doubt Becker's assertion," said Koch.

Bild said Becker was paid more than 100,000 Deutschmarks (equivalent to 50,000 euros or 70,000 dollars) for her information in the 1970s.

The official's son, chemistry professor Michael Buback, believes Becker, who was released from prison in 1989, was the assassin. (dpa)