Derek Marlowe. Somebody’s Sister (1974)
Walter Brackett, a transplanted English private eye now living in San
Francisco, investigates the death of a young girl, her life cut short when
her car crashes into the girders of the Golden Gate Bridge. Brackett soon
realizes that the wrecked car wasn’t hers—she was too young to be driving.
Then the only witness to the “accident” is murdered. Who was this young
girl, and was her death really an accident?