Americans who think the 9/11 commission is going to answer all the crucial questions about the terrorist attacks are likely to be sorely disappointed -- especially if they're interested in the secret evacuation of Saudis by plane that began just after Sept. 11.

We knew that 15 out of 19 hijackers were Saudis. We knew that Osama bin Laden, a Saudi, was behind 9/11. Yet we did not conduct a police-style investigation of the departing Saudis, of whom two dozen were members. of the bin Laden family. That is not to say that they were complicit in the attacks.

Unfortunately, though, we may never know the real story. The investigative panel has already concluded that there is ''no credible evidence that any chartered flights of Saudi Arabian nationals departed the United States before the reopening of national airspace.'' But the real point is that there were still some restrictions on American airspace when the Saudi flights began.

In addition, new evidence shows that the evacuation involved more than the departure of 142 Saudis on six charter flights that the commission is investigating. According to newly released documents, 160 Saudis left the United States on 55 flights immediately after 9/11 -- making a total of about 300 people who left with the apparent approval of the Bush administration, far more than has been reported before. The records were released by the Department of Homeland Security in response to a Freedom of Information Act request filed by Judicial Watch, a conservative, nonpartisan watchdog group in Washington.