FBI releases declassified documents on Sept. 11 attacks

The FBI released hundreds of pages of newly declassified documents Wednesday about its long effort to explore connections between the Saudi government and the Sept. 11 attacks, revealing the scope of a strenuous but ultimately fruitless investigation whose outcome many question to this day.

Agents for years investigated support given to several of the hijackers upon their arrival in the U.S., focusing in particular on whether three Saudi nationals -- including a Saudi Embassy official in Washington -- had advance knowledge of the attacks.

Ultimately, investigators found insufficient evidence to charge any of the three with illegally supporting the hijackers, according to an FBI memo from May that closed out the probe and was among the more than 700 pages released Wednesday. The FBI noted in the memo that al-Qaida compartmentalized the roles within its major attacks and "did not make the attack plans known in advance to others" for fear of word getting out.

"Specifically, in relation to the 9/11 attacks, the hijackers knew there was a martyrdom operation, but did not know about the nature of the operation until shortly before the attack for operational security reasons," the FBI memo states.

The documents were the latest materials to be released under an executive order from President Joe Biden aimed at making public long-classified investigative reports related to the attacks. A separate investigative document was released on the 20th anniversary of the attacks in September. The records have long been sought by victims' relatives as they sue in federal court in New York to try to prove that the Saudi government was complicit, something Riyadh officials have vigorously denied.