Family members of the September 11, 2001 attack victims have demanded a U.S. government watchdog investigate their strong suspicions that the FBI “lied about or destroyed” sensitive secret evidence linking Saudi Arabia to the terrorist attack. It comes as President Joe Biden, under huge pressure, signs an executive order tasking federal agencies to start declassifying documents into the FBI’s investigation.

The families’ demand which has been made in a letter to the Department of Justice Inspector General, Michael Horowitz, says "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 Federal Bureau of Investigation declined to comment on the letter.

The letter, signed by about 3,500 people, including families of victims, first responders, and survivors said "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" 

It asked Horowitz to investigate FBI statements 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 U.S. to the 9/11 hijackers."

This is latest in a series of requests over the past 20 years since the attacks in New York, Washington, and Pennsylvania, seeking the disclosure of evidence. The evidence includes phone records and a videotape of a party in California attended by two of the hijackers more than a year before the attacks.

Saudi Arabia has said it had no role in the hijacked plane attacks. The Saudi embassy in Washington did not immediately respond to a request for comment.

In an interview, Brett Eagleson, son of September 11 victim Bruce Eagleson says "our government is either lying about the evidence it has or it is actively destroying it, and I don't know what's worse".

Eagleson says many victims, like him, are not interested in tears or emotional speeches from politicians anymore. 

Eagleson says "this is a story about how angry we are. We are done with the emotional side. We want our government to finally help us,"

He added all the families want now is vital information about the attack and the ability to read all the secret government files related to that day.

Family members of the victims have long sought U.S. government documents, including secret law enforcement and intelligence reports, related to whether Saudi Arabia aided or financed any of the 19 people associated with al-Qaeda; the terror group Washington alleges was given safe haven by the Taliban in Afghanistan at the time. 

Fifteen of the 19 hijackers were from Saudi Arabia. A U.S. government commission in 2004 found little evidence that Saudi Arabia directly funded al Qaeda. The probe left open whether individual Saudi officials might have played a role. 

Family members of the victims say, since then, more evidence has emerged that implicates high-ranking Saudi officials’ involvement. 

Nearly 3,000 people were killed, including more than 2,600 at the World Trade Center, 125 at the Pentagon, and 265 others on the day of the attack. 

The families of roughly 2,500 of those killed, and more than 20,000 people who suffered injuries, businesses, and various insurers have already sued and taken legal action against Saudi Arabia.

They are seeking billions of dollars from the Kingdom. 

Last month, many families asked President Joe Biden to skip the 20-year memorial events, the anniversary of which is next week, unless he declassified documents they contend will show Saudi Arabian leaders supported the attacks.

Three days later, the Justice Department said in a court filing that it had decided to review earlier claims of privilege it had made about why it could not release some information requested by families.

In a statement last month, Biden claimed "my administration is committed to ensuring the maximum degree of transparency under the law". 

Succumbing to growing pressure, Biden has now ordered reviews of the potential declassification of documents from the FBI's investigation into the attacks.

"When I ran for president, I made a commitment to ensuring transparency regarding the declassification of documents on September 11, 2001, terrorist attacks on America," Biden says "as we approach the 20th anniversary of that tragic day, I am honoring that commitment."

Biden says his executive order will direct the Department of Justice and other agencies to "oversee a declassification review of documents" related to the FBI probe. 

He says the order requires Attorney General, Merrick Garland, to make the declassified documents public over the next six months.

Despite Biden’s executive order, and the ongoing demands of family members, experts are skeptical that any tangible results will be achieved saying the matter is connected to the deep state. 

Experts also say the release of any Saudi links to the attack will pressure the White House to cut all ties with Saudi Arabia, a staunch ally of the United States in West Asia.