A federal law enforcement agency released information about an official 9/11 probe on the 20th anniversary of the terrorist attacks.

The FBI unveiled the first detailed document on the subject, in response to President Joe Biden’s order on Sept. 11. BL can reveal it dates back to 2016 and explores Saudi government involvement with airplane hijackers whose actions resulted in nearly 3,000 deaths.

Up to 15 out of the 19 hijackers were Saudi Arabian nationals. Then al-Qaeda leader Osama bin Laden came from a prominent family in the kingdom, according to CNN.

Families of the victims and countless individuals injured from the attacks had sought billions of dollars of compensation from Saudi Arabia. They demanded that President Joe Biden declassifies the FBI investigation findings.

FBI agents had suspected Saudi student Omar al-Bayoumi was actually an undercover Saudi intelligence agent in Los Angeles. The bureau found he was heavily involved in helping two hijackers seek travel aid, accommodation, and financing.

Investigators ultimately concluded there was no evidence to suggested the Riyadh government directly funded al-Qaeda. They were also unable to confirm whether any Saudi official was directly involved in the attacks. A relevant commission suggested there was some “likelihood” of government-sponsored charities.

Saudi Arabia welcomed the FBI’s findings and promised to be completely transparency.

“As past investigations have revealed, including the 9/11 Commission and the release of the so-called ’28 Pages,’ no evidence has ever emerged to indicate that the Saudi government–or its officials–had previous knowledge of the terrorist attack or were in any way involved,” an embassy representative said according to Reuters.

However, several mourning American families still believe the Middle Eastern country’s administration could have been involved.

“Now the Saudis’s secrets are exposed, and it is well past time for the kingdom to own up to its officials’s roles in murdering thousands on American soil,” 9/11 Families United chairwoman Terry Strada said in a statement.