Clues Missed on 9/11 Plotters

And as many as eight of the hijackers entered the country with doctored passports that contained "clues to their association with Al Qaeda" that should have been caught by immigration authorities, commission investigators said.

The newly disclosed findings challenge previous claims by top CIA and FBI officials that the hijackers' records and paperwork were so clean that they could not have aroused suspicion.

The commission also heard testimony from a U.S. customs agent who blocked the entry of a Saudi citizen investigators now believe may have been the intended 20th hijacker.

Authorities later learned that Mohamed Atta, the leader of the Al Qaeda cells that executed the Sept. 11 attacks, was at an Orlando, Fla., airport that same day -- possibly waiting to meet up with the Saudi man, Mohammed Al-Qahtani, who is now in U.S.custody.

The disclosures were included in the first set of staff reports to be issued by the commission since it opened its inquiry last year, and came during a daylong hearing devoted to immigration and intelligence-related failures by government agencies.

Government witnesses described on Monday reforms that they said have shored up serious shortcomings in border security systems, visa screenings and information-sharing among agencies responsible for generating watch lists of suspected terrorists.

But commissioners and investigators on the panel voiced concern that certain agencies have not come to grips with the magnitude of the problems that allowed Al Qaeda operatives to slip past security systems and checks.

"We are not sure that these problems have been addressed," said Philip Zelikow, executive director of the commission, referring to failures to put Al Qaeda operatives on federal watch lists. "We are not sure they are even adequately acknowledged as a problem."

Also on Monday, President Bush identified an Al Qaeda operative caught in Iraq 12 days ago as a senior official in the organization who had close ties to Mohammed.