Until Sept. 11, Mohamed Atta was just another face in the crowd as far as the United States government was concerned. He entered the country perfectly legally in July 2001 as a nonimmigrant visitor and was still legal the morning he boarded American Airlines flight 11. His role with Islamic extremist groups in Hamburg Germany was unknown.
What's more, his situation was not uncommon. Among the 19 hijackers who boarded flights that day, 13 had entered the country in normal fashion - filling out all the forms, answering all the questions for student and visitor visas. And that is what has many people here shaking their heads.
For years, the Washington immigration debate has focused on the US's thousands of miles of unprotected borders and the quiet, undetected masses that slip into the country under cover of night or in the backs of trucks.
But the open, obvious way Mr. Atta and 12 others entered the US has exposed another huge hole in the nation's immigration system - on the legal side. Authorities are suddenly rethinking what changes in policy might be needed, starting with the most basic rules of granting visas.
More than 7 million people entered the country last year on visas, and some experts believe that if the government had been watching this group more closely, the Sept. 11 attacks might never have happened.
"Closer scrutiny would have made a difference, because dozens of people were involved," says Steven Camarota, director of research for the Center for Immigration Studies. "We can't get them all, but all you would need to do is get a few."
A restructuring of the way visas are granted has had several false starts, but it now seems inevitable. Most foreign nationals need visas to enter the US even as tourists - and they can get them with relative ease. Applicants for student and visitor visas simply fill out forms, provide pictures, and sit through what are often brief interviews. Fingerprints are not taken, and security checks are cursory at best.
The problem, says Mr. Camarota, is that the Bureau of Consular Affairs, which sorts through the applications, is short-staffed, and the workers it does have are judged by the number of interviews they conduct, not the rigor of the questioning.
Added to that mix is the relative inexperience of the people in those posts. Many of those working in the "Consular Corps" are newly-assigned, low-level Foreign Service hires who are not necessarily well trained. "This is the first stop for many who enter the Foreign Service," says Mark Miller, a political science professor and immigration expert at the University of Delaware.
Even if an application is denied, the lack of coordination between consulates means rejected candidates can simply "consulate hop" - try another office using a different name.
And once the visa holders are in the US, there is no system to determine where they are - whether students with visas are actually attending class, or even if visitors have left by the time their visas have expired. Some estimate that more than half of the illegal immigrants in this country are people who overstayed their visas. Three of the Sept. 11 hijackers had overstayed theirs.
Weeding out potentially dangerous applicants and preventing people from slipping into the country under false names and identities will likely mean a much tougher approach and more money - if proposals on Capitol Hill are any indication.
Along with more thorough interviewing, particularly for residents of watch-listed nations, some are recommending fingerprinting and using biometrics systems that record people's physical characteristics. The aim it to make it tougher for people to disguise themselves and allow agencies to compare photos of applicants to those on watch lists.
"It would not only help catch people," Camarota says, "it would be a deterrent. If you're a terrorist, you're not likely interested in giving the US government fingerprints and a nice photo."
Though none of the 19 terrorists involved in the World Trade Center and Pentagon attacks were on an FBI watch list, experts agree that such changes could make a difference. The point isn't to completely stop terrorists from entering the country, which is nearly impossible, but to keep them off balance.
The real test, however, may be whether Washington follows through on any of the proposed changes. In 1996, Congress passed a law that would have tracked when visa holders entered and left the country. It also would have created a database of people in the US on student visas.
Neither program was ever fully implemented due to political pressure. "The student measure in particular was resisted by universities, including the University of Delaware," Professor Miller says. "We have the capacity to make the changes we need. We just haven't had the political will."
But that reticence may no longer be an issue. Lawmakers are showing renewed interest in changing the system. "People are talking about this in a much more academic, serious way than ever before," says a Senate staffer. "People aren't just dismissing ideas, saying, 'You can't do that, that's Big Brother.' "
The real question now, the staffer says, is "what holes should we fill first." A key area being examined is better sharing of information between the FBI, the State Department, and the Immigration and Naturalization Service.
Yet even if the US tightens visa procedures, the nation would still be vulnerable to terrorists who enter the country illegally through Mexico or Canada. Tougher safeguards are coming there as well. The antiterrorism bill that passed the Senate last week included $609 million for new personnel along the Canadian border.