How he evaded capture for so long
Despite being the world's most wanted man, pursued by the most advanced military in history, Osama bin Laden evaded capture for almost a decade thanks to a secretive and ruthless protection system.
In the immediate aftermath of the terrorist attacks of September 11, 2001, bin Laden is thought to have moved between Kandahar and Kabul, in Afghanistan, arranging the exit and financial backing of allies.
Three months after the attacks, he survived the aerial bombardment by the US air force of the cave complex in the mountains of Tora Bora, in which he was widely assumed to be hiding.
For almost ten years, it had been generally thought that he and a cabal of close aides slipped across the nearest point of the Pakistani border, probably assisted by rogue Pakistani law enforcement officers.
But a report based on intelligence gained from a detainee in Guantanamo Bay, released just last week by Wikileaks, suggested that bin Laden in fact headed in another direction, towards Jalalabad.
The report suggested that he stayed there in a safe house – while a $25 million (£15 million) bounty hung over his head – before heading towards the remote province of Kunar, in north-east Afghanistan.
It was said that bin Laden escaped with help from a Pakistani militant and cleric called Maulawi Nur Muhammad, who provided up to 50 fighters to escort him and Ayman al-Zawahiri, his deputy.
The al-Qaeda chief is thought to have then stayed in Kunar, a violent and generally ungovernable area, before again crossing the border into Pakistan in late 2002.
Since then, the life of bin Laden – and the activities of US forces assigned to capture him – have remained mysterious, with critics baffled that George Bush, and later Barack Obama, failed to find him.
Known to his close followers as "the sheik", and surrounded by 40 bodyguards, bin Laden was said to have moved with utmost care around the tribal-run border regions between Afghanistan and Pakistan.
It was reported that the personnel protecting bin Laden had an agreed code word that, when uttered, would signify that enemy forces were approaching and that they must martyr themselves.
Reports suggested that on at least one occasion, US troops came very close to bin Laden's compound, prompting intense disquiet among the terrorist leader's circle. But they never came close enough.
For all the billions of dollars ploughed into intelligence, high-tech assaults and drone attacks by the US, bin Laden had on his side an intensely loyal following and a biddable local population that was no friend to Washington.
Bin Laden, a wealthy heir flush with jihadists' cash, was reported to have paid millions of US dollars to local tribesmen, who had already promised to help the US military, to instead assist him and al-Zawahiri in their exile.
At the same time, the White House depended on Pakistan – led for much of the period by the erratic Pervez Musharraf – for assistance, despite widespread knowledge that significant portions of its intelligence service was sympathetic to al-Qaeda.
In recent years bin Laden was rumoured to have suffered from serious kidney problems, leading to frequent rumours of his demise. Yet he persistently re-appeared on video to pass comment on US foreign policy and other world affairs.
Last night it appeared that, in the face of longstanding and intense US attacks on the tribal regions, bin Laden had been forced to flee to the town of Abbottabad, north of Islamabad. There, the intense secrecy surrounding his movements would have been far more easily breached.
His apparent hideout was, for instance, close to a cinema, a police station and a hospital for women and children. In the wilds of the tribal regions his operation might have gone largely unnoticed. But it appeared that working from here, apparently in a mansion with no external communications, where residents burned their rubbish, was too much: too many suspicions were aroused.