Justin Elliot writes:

No small part of the public discourse surrounding Sept. 11, 2001, has been polluted by Truthers — those who believe that the attacks were an “inside job,” or that World Trade Center Building 7 was destroyed in a “controlled demolition,” or that the Pentagon was hit by a cruise missile, despite no compelling evidence for any of these theories.

Perhaps the most corrosive effect of the 9/11 conspiracy theorists is that they have distracted attention from real unanswered questions about the attacks.

Here, we look at some of the most important of those questions. This is not meant to be a comprehensive list.

What’s in the famously redacted 28 pages?

A joint inquiry of the House and Senate intelligence committees produced an 800-plus page report on activity of the intelligence community in connection with the 9/11 attacks, completed in December 2002. But 28 pages were redacted in the public version, all in the section titled “Finding, Discussion and Narrative Regarding Certain Sensitive National Security Matters.” It has been widely reported that those pages — which neither the Bush nor Obama administration have declassified — deal with links between 9/11 hijackers and Saudi government officials. Newsweek, for example, reported that the section “draws apparent connections between high-level Saudi princes and associates of the hijackers.”

As long as those pages remain classified, though, it’s impossible to assess the nature of those connections.

What was the role of the Saudi government?

Short of getting a look at those redacted 28 pages, the best source of information on this crucial question is the “The Eleventh Day,” a new account of 9/11 by journalists Anthony Summers and Robbyn Swan. Bob Graham, the Florida senator who co-chaired the joint inquiry, told the authors that the investigation found evidence “that the Saudis were facilitating, assisting, some of the hijackers. And my suspicion is that they were providing some assistance to most if not all of the hijackers. … It’s my opinion that 9/11 could not have occurred but for the existence of an infrastructure of support within the United States. By ‘the Saudis, I mean the Saudi government and individual Saudis who are for some purposes dependent on the government — which includes all of the elite in the country.”

That’s from an excerpt of the book recently published in Vanity Fair.

There has been particular interest in a San Diego-based Saudi national named Omar al-Bayoumi, who in California had extensive contacts with — and gave money to — the first two hijackers to enter the United States, Khalid al-Mihdhar and Nawaf al-Hazmi. Bayoumi, along with two other Saudis of interest, was interviewed by commission staffers in Saudi Arabia in 2003-04. None was ever charged with a crime.