Nineteen killers leave trail of clues

The investigation

US authorities have made their first arrests in connection with last week's suicide attacks in New York and Washington. A man arrested in New York on Thursday after being found with a pilot's licence issued to his brother is a "material witness", the city's police department has said.

Yet so far there are scant results – in public at least – from the huge-scale investigation that the US has launched, code-named "Penttbom". A vast amount of information has been compiled about the 19 men who hijacked the aircraft that plunged into the World Trade Centre, the Pentagon and a Pennsylvania field. But much remains opaque, including their true origins, motives and links.

The FBI, headed by Robert Mueller, has conducted more than 30 searches, issued hundreds of subpoenas, and seized computers, documents and piles of evidence. It has received more than 36,000 leads and compiled a list of more than 100 names of people it wants to question. It has issued search warrants to internet service providers across America, including America Online, Microsoft and Yahoo!. Agents have traced about $50,000 worth of plane tickets charged on credit cards.

The suspects were aged from their early 20s to their late 30s. Their neighbours described them – as always – as quiet, normal people. Twelve or 14 of them had lived in Florida at some point, according to reports. Many had learned to fly at schools in the state.

They had all used the anonymous, transient nature of US society to fit in and plan their operations. They used the local mail and stationery shops that are so common in the US as accommodation addresses and places to do business. A few of the suspects had suburban family homes. Most lived in the motels, hotels, short-term rental apartments and transient condominium blocks so typical of Florida. They paid cash, in advance, for nearly everything.

Several booked their final airline reservations on the internet. They used credit cards and frequent-flier numbers and they flew first or business class. Two of those on the flight that hit the south tower of the World Trade Centre paid United Airlines $4,500 each for one-way first-class seats. Some had been in the US for more than five years. Either they had planned the operation with meticulous care since 1996, or sleepers had been planted, or men with no previous connections to any group were recruited.

Saeed Alghamdi, one of the four listed as hijacking United Airlines Flight 93, which crashed in Pennsylvania, seems to have been in the US for about eight years, living in Florida. He held a driving licence issued in Saudi Arabia. He appears to have shared an apartment with Waleed al-Shehri, another suspect, who had been in the US since at least 1994. Al-Shehri may also have lived for a time in Vienna, Virginia, a plush suburb of Washington – only three blocks from the headquarters of the CIA. Mohamad Atta, 33, is claimed by the FBI to have been one of the ringleaders. Among the luggage that he left behind at Boston's Logan Airport was a will that said he would martyr himself. It was written as long ago as 1996.

The men's countries of origin have been variously listed as Saudi Arabia, the United Arab Emirates, Afghanistan and Egypt, but there is mystery over their real identity. Several of the hijackers listed Saudi Arabian Airlines as their sponsor while they attended flight schools. And a defence official told US media that two of the hijackers were former Saudi fighter pilots who had studied in exchange programmes at Lackland Air Force Base in Texas and the Air War College at Maxwell Air Force Base in Alabama.

Two of the hijackers, Waleed al-Shehri and Wail Alsheri, are alleged to have been the sons of a Saudi diplomat. Saudi nationals are usually given relatively free access to the US, as the country is considered an ally. Saudi Arabia is very sensitive about the involvement of its nationals in terrorism; Osama bin Laden himself was a Saudi, though the government has stripped him of citizenship.

Gaafar Allagany, a spokesman for the Saudi government, told the Boston Globe that none of the hijackers were sponsored or employed by the government-owned Saudi Arabian Airlines. "If they come to America, they have to come through the office of Saudi Arabian Airlines. They never heard of these names," he said.

There are indications that at least some of the 19 were using aliases. Abdulaziz Alomari, for example, was on the passenger list of Flight 11, next to Mohamad Atta. But a Saudi journalist told the Globe that Abdulaziz Alomari is a real pilot alive in Saudi Arabia who claims his identity was stolen by one hijacker. Al-Hayat, a London-based Arabic newspaper, says Atta was an Egyptian, but investigators found a Saudi passport in his luggage.

Not all fit the fundamentalist stereotype. Some had been seen drinking at local bars. Atta had caused a fuss over the bill at a bar near Hollywood, Florida, two weeks ago, according to reports.

French media said that a man arrested in Belgium had planned attacks on US interests in France, including the Paris embassy. The radio station Europe 1 said he was one of six suspected extremists arrested in Brussels and Rotterdam as European police forces cracked down on possible guerrilla networks.

Yet, despite intensive police activity from Manhattan to Manila, the results so far have been thin. And fears are building that in their zeal to arrest suspects, police will trample over legal niceties and pull in anyone with an Arabic name.