In the six months since Sept. 11, police across the United States and Europe have arrested nearly 1,400 people in connection with the attacks on New York and Washington. But they have charged only one of them in connection with the worst terrorist outrage in history.
No Al Qaeda cells have been uncovered in the US, while in Europe only seven men picked up since Sept. 11 have been served with formal charges related to Islamist terrorism. Seventy-eight more are in jail, pending the outcome of investigations ranging from credit-card fraud to an alleged plot to blow up the US Embassy in Paris. But only eight of those are suspected of involvement in the destruction of the World Trade Center.
The meager results of the most intensive and widespread criminal investigation ever mounted have raised questions about whether traditional law enforcement and judicial procedures can cope with international terrorism.
"The low visible yield does not bode well for future efforts like this," says Michael Levi, professor of criminology at Cardiff University in Wales.
Indeed, the difficulties of tracking down suspects and amassing sufficient evidence to convict them leads some experts to wonder whether it is worth it. "Is terrorism a crime or is it war?" asks Stephen Gale, a counterterrorism expert who teaches at the University of Pennsylvania. "If you think someone is going to take out your electrical grid, in a criminal investigation you arrest him. In a war you shoot first and ask questions later," he points out.
While US officials believe some top Al Qaeda leaders may have been killed in the war in Afghanistan, criminal investigations at home and in Europe have enjoyed no such success. Only one of the men in custody on suspicion of terrorist connections Abu Qutada, a Jordanian being held in London is thought to be a ranking member of Osama bin Laden's organization, and he has not been charged with any crime. The rest are suspected of being, at most, low-level members of Al Qaeda's loose-knit network, with little or no knowledge of future plans.
The disappointing haul does not mean that Al Qaeda cells are less widespread than authorities thought, say European law enforcement officials, nor that the police do not have very strong suspicions about some individuals they are watching or holding. But they have been unable to turn those suspicions into formal accusations in many cases because of the particular difficulty of mounting terrorist cases.
Seeking those involved in the Sept. 11 events is especially hard, says Professor Levi, because reconstituting a terrorist network post facto is nearly impossible if members used ephemeral means such as the Internet to communicate. "This is not like a normal, organized crime case, where you round up the suspects after surveillance," Levi explains. "The people involved in this were not suspected before, so they weren't being watched, and much of the evidence will have disappeared."
Convicting members of Al Qaeda-style networks in order to preempt further attacks is hardly easier, even when they are under surveillance, suggests Michael Clarke, head of the Centre for Defence Studies at London University.
"Terrorism poses a fundamental challenge to the legal system," Professor Clarke argues. "Terrorists often do nothing indictable till they commit the act. Ninety percent of the time sleepers are absolutely legal, so you can't do anything about them even if you know who they are.
"Terrorism challenges our categories of what is legal and what is illegal," Clarke adds.
Though the US and European authorities reacted differently to Sept. 11, neither approach appears to have produced many indictable criminals. US agents quickly swept up more than 1,100 suspects in the wake of the attack, hoping that a wide dragnet might catch some terrorists. Some 326 remained in the custody of the Immigration and Naturalization Service as of Feb. 15, according to the Justice Department, and 114 more face charges ranging from check forgery to possession of false IDs, but none have been charged with terrorist-related offenses.
Richard Reid, the so-called "shoe bomber," was subsequently charged with attempted murder after allegedly trying to blow up a flight to Miami.
Zacarias Moussaoui, the only man facing charges in the US relating to Sept. 11, and who is said to have been the missing "20th hijacker," was arrested in Missouri in August, and was thus in jail when the attacks happened.
In Europe, where the police were more cautious, only 245 people were arrested partly because of stricter laws concerning detention. In Germany, for example, where suspected lead hijacker Mohammed Atta and two fellow hijackers lived in Hamburg for some time, only two men are being held, including the only man charged with involvement in Sept. 11th, Mounir al Motassadeq, a Moroccan accused of providing logistical support for the terrorists.
"Not everybody who had contact with the Hamburg people is a suspect we can arrest and put behind bars," says Srauke-Katerin Scheuten, an official at the German federal Public Prosecutor's office. Prosecutors must have "serious" suspicions that they can back with "concrete proof" in court, she adds. German police do not have the power to arrest "material witnesses," as their US counterparts do.
Sometimes, even serious suspicions and apparently concrete proof can evaporate in the face of challenges from a defense lawyer, as happened in the case of Lotfi Raissi, whom a British court last month refused to extradite to the US.
US officials had branded Mr. Raissi, an Algerian airline pilot, a "lead instructor" of the Sept. 11 hijackers, saying they had video of him with Hani Hanjour, who allegedly piloted the plane that crashed into the Pentagon; records of phone conversations between the two men; evidence that they had flown a training plane together; and evidence that Raissi had met several of the hijackers in Las Vegas.
It turned out, the British court found, that the video showed Raissi with his cousin, not Mr. Hanjour, that Raissi had mistakenly filled in his air training logbook and had never flown with Hanjour, and that Raissi and the hijackers were not in Las Vegas at the same time. The US authorities never presented any phone records showing conversations between Raissi and Hanjour.
Although it appears that in this case the US authorities handed over all the information they had, in others they might be reluctant to compromise intelligence sources in order to secure a conviction, legal observers say. "In courtroom procedures, you have to reveal all your intelligence sources and methods in discovery," says Professor Gale. "They are going to have to open up their entire intelligence files in the Moussaoui case, or he walks."
This poses an additional obstacle for prosecutors, who need more evidence of wrongdoing to secure a conviction than do intelligence agents, who often act on suspicion. "The differences between intelligence work and criminal justice is getting to be a bigger general problem," says Levi.
That became clear in Northern Ireland, where a number of convicted Irish Republican Army suspects have been freed over the years because evidence supplied by the British intelligence services turned out to be unreliable.
Gathering good intelligence about terrorists is always hard. It took French authorities who have enjoyed considerable success in dismantling Algerian terrorist groups in France several years to penetrate the groups they were pursuing. And after years of work, US investigators came no closer to identifying the Unabomber until his brother turned him in.
Infiltrating a loose-knit network of tightly grouped cells, such as Al Qaeda, presents even greater difficulties, and the European police have not yet been able to get very deep. Almost all those arrested since Sept. 11 had already been on their watch lists.
Mass arrests after Sept. 11, says intelligence expert Guillaume Dasquié, "were designed for public consumption. But they served no real purpose, because they picked up people who were already under surveillance, which means they can't have been involved in Sept. 11, unless the surveillance was very poor."
In Italy, for example, all the 24 people arrested since Sept. 11 have been detained in connection with cases that investigators opened a year ago, well before the attacks on New York and Washington.
Given the difficulties involved in tracking and jailing terrorists through conventional means, "we are going to have to invent new ideas about what war is, and that will have far-reaching implications for the legal system," says Gale. The battle against terrorism, he argues, "has nothing to do with" traditional legal and criminal investigations, which he calls "superfluous."
More cautiously, Clarke suggests that "the legal route is an adjunct to other ways of dealing with the problem," such as seeking to disrupt terrorist networks through deportations and other forms of harrassment. But the slow progress prosecutors in the US and Europe have made along that route, he acknowledges, "is a sobering reflection on the nature of the problem."
Isabelle de Pommereau in Frankfurt and Courtney Walsh in Rome contributed to this report.