WASHINGTON (AP) - An accused leader of al-Qaida in Europe - who can take on the appearance of a Westerner when he wants to - is getting fresh scrutiny in the London bombing investigation, thanks to his globe-hopping travels and associations that read like a who's who of international terrorism.
Authorities have few clues about the location of Mustafa Setmarian Nasar, whom British officials once had in their grasp and on whose head the United States has put a price of up to $5 million.
Nasar's background and travels, described in detail by Western officials and in court and intelligence documents, make him a case study of the intricate connections that tie Muslim extremists around globe and the challenges in tracking highly mobile and easily disguised suspects. He's a Syrian native and a Spanish citizen.
International intelligence agencies have traced Nasar's movements to Syria, Afghanistan, Iran, Iraq and at least two European capitals. His name emerged shortly after London's July 7 bombings as a possible suspect, though any ties to those attacks remain unclear at best.
A U.S. official, who spoke on condition of anonymity while the London investigations continue, said Nasar's record suggests he is more of an ideologue and writer than operational planner. Yet he has a network of dangerous international contacts, and authorities haven't eliminated the possibility that he plays a role in operations.
He was once in British custody for suspected involvement in bombings that rocked Paris in 1995. Lacking evidence, the British let him go.
Spanish authorities allege he played a key role in setting up al-Qaida's structure there and may have been the mastermind of the 2004 Madrid train bombings, which killed 191. Interpol has issued an international arrest warrant.
Nasar's 2004 book, ``The International Islamic Resistance Call,'' lays out in 1,600 pages strategies for attacking Islam's enemies. He lists those as ``Jews, Americans, British, Russian and any and all of the NATO countries, as well as any country that takes the position of oppressing Islam and Muslims,'' according to a translation from the Washington-based SITE Institute.
Rita Katz, director of the institute, which studies terror groups, said the autobiographical book and related videos are a how-to for radical ``holy warriors.''
``His brain is out there for the mujahedeen to use,'' Katz said. ``He has his fingerprints everywhere on the globe because he is one of the foremost experts on urban warfare.''
Nasar's dual Spanish-Syrian citizenship and his Western appearance have aided his elusiveness. The 46-year-old can take on the looks of an Irish pub patron - red hair, light skin, stocky build. When he grows out his beard, Nasar - whose aliases range from Abu Musab al-Siri to Blond Blond - blends into Islamic society.
His journey into extremism began in the 1980s when he joined radical groups including the Syrian Muslim Brotherhood, which has opposed the Syrian government and developed ties with terror groups.
By 1988, Nasar was with the mujahedeen fighting the Soviet invasion of Afghanistan, where he met Osama bin Laden and became a leader of the Syrians associated with early al-Qaida, Spanish court documents say. When bin Laden moved his operations to Sudan in 1991, Nasar was known to visit.
In the 1990s, Nasar deepened his European roots, living at various points in Madrid and London. Spanish police put him under surveillance in 1995. In the middle of that year, Nasar packed up for London.
Spanish court documents show that police watched as Nasar's wife moved their furniture, borrowing a Ford Fiesta and other cars belonging to close associates of Imad Eddin Barakat Yarkas. A Syrian-born Spaniard, Yarkas went on trial in April on charges of using Spain as a staging ground to help plot the Sept. 11, 2001, attacks.
Soon after Nasar's move, Paris was hit by a series of subway attacks carried out by the Algerian Armed Islamic Group. Nasar helped edit the group's al-Ansar newsletter, meaning ``the supporters.''
The British Secret Service detained him as a possible suspect in the attacks, according to German and Spanish investigative documents, but he was later released.
Nasar was running a training camp financed by bin Laden and keeping close contact with Taliban leader Mullah Omar by late 1997, according to Spanish intelligence documents and U.S. officials.
He was believed to be in Afghanistan at the time of the 9/11 attacks on New York and Washington - which he says were predicted by the prophet Mohammed as events leading to victory for Islam. ``The duty of jihad is a must until the end of days,'' he wrote.
Only then did Nasar formally pledge allegiance to bin Laden. When the U.S.-led invasion disrupted al-Qaida's Afghan base, Nasar was thought to be among a number of fighters pushed across the border to Iran, said a U.S. defense official, who spoke on condition of anonymity because of the information's sensitive nature.
The official said Nasar was eventually asked to leave.
Spanish authorities say he may have played a pivotal role in the Madrid railway bombings. Among evidence, Spanish legal documents say an alleged cell member had Nasar's bank account number in his notes at home.
Western intelligence authorities do not know where Nasar is today.
The defense official said he apparently traveled to Iraq after Saddam Hussein's fall - possibly as late as last summer. Other reports place him in Afghanistan or Pakistan.