The trail that led the CIA to Osama bin Laden began with his most trusted courier. It had taken the CIA years to discover first his name and then the home where he was hiding bin Laden. But it took only 40 minutes on Sunday for US special forces to kill both the courier and bin Laden.
Contrary to repeated speculation over the last decade that bin Laden was living in one of the remote tribal areas of Pakistan or even across the border in Afghanistan, the al-Qaida leader was found in an affluent suburb of Pakistan's capital, Islamabad.
Senior US administration officials, briefing journalists in a late-night teleconference, said that after 9/11 the CIA chased various leads about bin Laden's inner circle, in particular his couriers. One of these couriers came in for special attention, mentioned by detainees by his nom de guerre and said to be one of the few couriers bin Laden trusted.
But officials said they were initially unable to identify him but finally did four years ago. They did not disclose his name to reporters Sunday night.
Two years ago, the CIA found the rough location where the courier and his brother lived in Pakistan, and on August last year they narrowed it down to a compound, in an affluent area about 35 miles north of Islamabad.
They realised immediately this was no normal residence. The walls were 12-18ft high, topped with barbed wire. Access to the compound was severely restricted. The main part of the residence was three storeys high but had few windows. It was valued at about $1 million but had no phone or internet connection. It was a custom-built terrorist hideaway.
Adding to their suspicions were that the two brothers had no known source of income. The CIA learned too that there was a family living with them and that this family matched bin Laden's.
By February, the CIA was confident this was bin Laden's likely hiding place and in March Barack Obama began chairing a series of five national security meetings. At the last of these, on 29 April, he gave the order to mount an operation.
The US military began planning. One of the senior administration officials said: "The high walls made this a dangerous operation." It was a surgical operation, he said, carried out by a small team and lasted only 40 minutes.
Bin Laden and three males were killed, including the courier and his brother, and bin Laden's son. Bin Laden resisted the US force and was killed in a firefight, an official said.
One woman was injured while, an official said, she was being used as a shield by one of the men, and two other women were also injured.
The US force ran into a problem with one of their helicopters which had to be abandoned, but only after being destroyed by explosives set by the American troops.
