Ten days before the 9/11 terror attacks on New York City, Prince Turki retired from his post as head of Saudi intelligence. It was an abrupt departure, well before his tenure was due to expire.
Did Prince Turki know of the impending incident, and did he alert US intelligence ( John Brennan ) , which then did not take appropriate action to prevent it?
Jamal Khashoggi had long served as a trusted media advisor to Prince Turki,
https://www.zerohedge.com/news/2018-10-14/did-saudis-cia-fear-khashoggi-911-bombshell
Brennan was deputy DCI at the time, having risen from being the DCI's (George Tenet's) chief of staff. Before that, he had been CIA station chief in Riyadh (from 1996 to 1999).
The fact that a guy like Brennan could be a CIA officer is proof that background checks and lie detectors are a waste of time!