Worldwide hunt for hijack plotters

The biggest manhunt in US history is unlikely to be over quickly.

The investigation has many strands, and the thousands of agents involved are engaged in tasks as varied as sifting through rubble, and trawling through millions of electronic, possibly encoded, messages.

The pieces of the jigsaw are scattered all over the world, mirroring the organisation of the chief suspect, Saudi dissident Osama Bin Laden, which is believed to operate in more than 40 countries.

Sifting through rubble: FBI evidence team outside the Pentagon

The FBI says it already knows the identity of many of those involved - the 19 hijackers, who all died in the suicide attacks, as well as dozens more who may have helped to execute the complex plan.

These may include drivers, couriers, and people assigned to obtain airport passes, or to study flight schedules and the on-time records of trans-continental flights.

Retracing their movements, gathering clues they left on the way, and ultimately tracking down those who are still alive, is one of the key elements of the investigation.

There is also a massive effort to trace other potential hijackers, especially any recently trained to fly aircraft, on the assumption that further attacks may be being prepared.

In total, investigators have a list of more than 100 people they want to interview - it has been sent to airports and law enforcement agencies but not made public.

Passenger lists

The first important arrest in the US, of an unnamed man, was made on Friday, three days after the attacks. Two other men were detained in Texas and taken to New York.

Police arrested a second unidentified man on Saturday at apartment in New Jersey across the Hudson River from New York.

In an effort to block off escape routes, Mexican officials are reported to be on the lookout for up to nine men with Pakistani passports who may attempt to cross into or leave the country.

Hijacking suspects

Flight 175: Marwan Al-Shehhi, Fayez Ahmed, Mohald Alshehri, Hamza Alghamdi and Ahmed Alghamdi

Flight 11: Waleed M Alshehri, Wail Alshehri, Mohamed Atta, Abdulaziz Alomari and Satam Al Suqami

Flight 77: Khalid Al-Midhar, Majed Moqed, Nawaq Alhamzi, Salem Alhamzi and Hani Hanjour

Flight 93: Ahmed Alhaznawi, Ahmed Alnami, Ziad Jarrahi and Saeed Alghamdi

Agents are also investigating whether some of those involved may have crossed into the USA from Canada.

The state of Maine, just south of the border, was the jumping off point for two of the hijackers who flew in one of the planes from Boston that crashed into the World Trade Center.

Agents have requested lists of passengers travelling via the ferry from Nova Scotia, for the entire season, as well as checking mobile phone purchases.

Fourteen of the hijackers have also been traced to Florida, where their homes in the Miami suburbs and other nearby towns have been pulled apart.

Three suspects have been tracked even further back, to Hamburg in northern Germany, where the flats they lived in were searched on Wednesday night.

Click here to see a map of the flight paths

A Saudi flying student Adnan Bukhari was questioned in Florida, but later released. A man thought to be his brother was later seized in the Philippines.

Arrests have also been made in London, Rotterdam and Brussels, though little information has been given away about those seized.

Investigators raided a hotel in the Philippines in search of a group of Omanis, and police in Thailand say they are on the lookout for 15 Arab men.

DNA tests

Everything the hijackers are known to have touched is being regarded as evidence.

Bags of materials were removed from the Florida homes they vacated shortly before the attacks.

A man was arrested in Hamburg, but later released

Two hire cars left by suspects at Portland airport in Maine, and at Boston's Logan airport, are being closely examined - the latter had an ashtray full of cigarette butts, presumably with saliva traces that can be used for DNA testing.

Even the seats some of the hijackers are believed to have sat on at Boston airport have been taken away for forensic study.

One of the factors that prevented US intelligence finding out about the operation before it was launched, was the failure of anyone involved to break ranks and come forward with information.

Another was the failure of electronic surveillance to pick up clues from e-mails or telephone conversations.

Following the attacks the FBI has been inundated with calls and tips sent to its website, but it has not been revealed whether any of these have been from people with real knowledge of the operation.

Officials claim that electronic surveillance in the last few days has given them reason to believe that Osama Bin Laden - already the US's most wanted terrorism suspect - was involved.

But they will also be searching retrospectively for communications about the hijackings, made before they took place.

This involves getting internet service providers to hand over information about where messages were sent from.

Couriers

If investigators are correct that Osama Bin Laden helped to mastermind the attacks, the very nature of his organisation may complicate their task.

FBI picture of Osama Bin Laden: His exact location is unknown

Experts say that while it is large - with more than 3,000 members - it lacks any clear command structure, and may have engaged in this case in a co-operative effort with another organisation.

Having given up using mobile telephones some years ago, Mr Bin Laden then turned to internet communications, but is now said to favour the more secure, low-tech method of using human couriers.

It is not known exactly where he is, and US attempts to hit him, or the Afghan bases where he trains volunteers, in a missile strike after the 1998 embassy bombings in Kenya and Tanzania, were a failure.

The most important evidence emerging from the rubble is contained in the black boxes - or flight recorders - which record flight data, and cockpit conversations.

Both recorders have been recovered from two of the aircraft: Flight 77 which crashed into the Pentagon, and Flight 93 from Newark, which crashed in Pennsylvania.

Together with the descriptions given by passengers, in their last frantic telephone calls, they will help to reconstruct events in the minutes leading up to the crashes.

However, unless the hijackers gave away clues about their leaders, or their organisation, this may not bring investigators much closer to their goal.

---

Click here to return