Former investigators on the 9/11 Commission, which uncovered tantalizing but inconclusive evidence of Tehran's ties to the plot, tell The Daily Beast they welcome the lawsuit, because they believe the U.S. government has done little to follow up on the commission's evidence of Iranian complicity.

Dietrich Snell, a former top terrorism prosecutor at the Justice Department, who says in his affidavit that "there is clear and convincing evidence the government of Iran provided material support to al Qaeda in the planning and execution of the 9/11 attack." He said the support came in the form of "facilitating the travel of members of the 9/11 conspiracy to and from Afghanistan and Pakistan, in which countries, in my opinion and as found by the 9/11 Commission, the plot was hatched and developed."

Former commission staffers say that much of the rest of the NSA's pre-9/11 terrorism database remains unreviewed to this day, suggesting that many of the other secrets of 9/11 may remain hidden in the agency's files.