Mystery of DB Cooper air stewardess who was sent to a Nunnery... but was it part of a witness protection programme? It is America's most notorious unsolved criminal case which, over the past four decades, has had enough twists and turns to match any film script. So it is not entirely surprising that the latest revelation is one straight out of Hollywood. The stewardess who famously dealt with the elusive DB Cooper during the Northwest Airlines hijacking and robbery of 1971 spent more than a decade in a Nunnery, in what experts believe was part of a witness protection programme....