A US government watchdog has been asked by family members of victims of the Sept. 11, 2001, airplane attacks to investigate their suspicions that the FBI lied about or destroyed evidence linking Saudi Arabia to the hijackers involved in the attacks.
Their request, which came in a letter to Department of Justice Inspector General Michael Horowitz on Thursday, said "circumstances make it likely that one or more FBI officials committed willful misconduct with intent to destroy or secrete evidence to avoid its disclosure."
The FBI has so far declined to comment on the letter, which seeks evidence including phone records and a videotape of a party in California attended by two of the hijackers over a year before the attacks.
"Given the importance of the missing evidence at issue to the 9/11 investigation, as well as the repeated mishandling by the FBI of that evidence, an innocent explanation is not believable," said the letter, signed by about 3,500 people - families of victims, first responders and survivors.
It urged Horowitz to probe the statements the FBI made in response to a subpoena from the families that the agency "lost or is simply no longer able to find key evidence about the individuals who provided substantial support inside the US to the 9/11 hijackers."
Saudi Arabia has denied involvement in the attacks, in which nearly 3,000 people were allegedly killed when hijacked planes crashed into New York's World Trade Center, the Pentagon outside Washington, DC, and a field in western Pennsylvania.
Families of the victims believe some Saudi officials were either complicit in the attacks or aware of the kingdom’s support for some of the hijackers.
The Saudi embassy in Washington did not immediately respond to a request for comment.
"Our government is either lying about the evidence it has or it is actively destroying it, and I don't know what's worse," Brett Eagleson, son of Sept. 11 victim Bruce Eagleson, said in an interview.
Last month, many families asked President Joe Biden to skip 20-year memorial events unless he declassified documents they argue will show Saudi Arabian leaders supported the attacks.
Three days later, the Justice Department said in a court filing that it would review earlier claims of privilege it had made about why it could not disclose some information families requested.