The biggest manhunt in history came to its bloody end when US special forces killed Osama bin Laden with a single shot to the face, moments after storming his purpose-built hideout in Pakistan.
In a last act of desperation, the al-Qa'ida leader had picked up an automatic weapon and begun firing at US Navy Seals before he and his bodyguards were swiftly overwhelmed.
The helicopter-borne assault on the compound in Abbottabad, 35 miles north of the Pakistani capital Islamabad, was carried out with such clinical precision that the Seals, carrying Bin Laden's body, were on their way back to base within 40 minutes of landing.
Yesterday, after President Barack Obama announced to the world that Bin Laden had been killed, extraordinary details began to emerge of an operation that had been months in the planning.
The initial breakthrough in the 13-year hunt for Bin Laden came four years ago, when the CIA discovered the identity of a man believed to be a trusted courier of Bin Laden, and his main link to the outside world.
The courier's nom de guerre had been mentioned numerous times by detainees at Guantanamo Bay in previous years, who described him as a protege of Khalid Sheikh Mohammed, the self-confessed mastermind of the 9/11 attacks.
But it was only when one of the Guantanamo detainees gave up the suspect's birth name that real progress was made.
It took another two years to establish in which part of Pakistan he operated. Eventually, in August last year, Mr Obama was told that the courier's home in the military garrison town of Abbottabad had been identified.
"It was a 'Holy cow!' moment," said one US official. Even the most cursory examination of the compound where the courier lived with his brother, another al-Qa'ida operator, and 20 other people was enough to make CIA analysts' hair stand on end.
The property, built at the end of a dirt track, was eight times larger than any other residence nearby. It had cost an estimated $1m (€670,000) to build, yet the brothers had no discernible income. Nor did the grand residence have any telephone or internet connections.
Moreover, the three-storey building was protected by two security gates and 12-18ft walls topped with barbed wire, and had a terrace hidden from view by a 7ft wall -- high enough to hide someone who was 6ft 4ins tall, such as Bin Laden.
Months of surveillance followed, by the CIA, the National Security Agency and the National Geospatial Agency, which showed that a third family lived in the compound, matching the profiles of the al-Qa'ida leader, his youngest wife and one of his sons.
In September, the final piece of the jigsaw fell into place when facial recognition software identified Bin Laden (54) from satellite pictures as he exercised outside. By mid-February, intelligence from multiple sources was clear enough for Mr Obama to "pursue an aggressive course of action", a senior US official said.
Military chiefs suggested using two B2 Stealth bombers to drop more than a dozen 2,000lb JDAM (Joint Direct Attack Munitions) on the compound, or launch a drone attack.
Mr Obama decided against it, partly to avoid civilian casualties and partly because: "He wanted proof. He didn't want to just leave a pile of rubble."
Between March 14 and April 28 Mr Obama chaired five National Security Council meetings to discuss the raid.
An exact replica of the compound was built at a secret location in the US and a 24-strong team of Navy Seals carried out two recent dummy runs. Mr Obama approved the plan for a helicopter-borne assault at a meeting in the White House Situation Room on April 19, and ordered the Seal team to fly to Pakistan and be ready.
At 8.20am local time in Washington last Friday, Mr Obama gave the "go" order to his national security adviser Tom Donilon, who passed on the permission to Leon Panetta, the CIA director.
The raid was scheduled to leave from Ghazi, near Islamabad, on Saturday, at a time of "low loom" -- little moon luminosity -- so the US helicopters could fly low to the ground and undetected. In the event, the raid was delayed by bad weather and put back by 24 hours.
At 8.30pm Irish time on Sunday (1.30am in Pakistan) four helicopters, believed to be Black Hawks, carrying the Navy Seals, hovered over the compound, already under fire from Bin Laden's guards.
As the Seals began to abseil on to the roof of the main building, and with Mr Obama watching the raid in real time from the Situation Room, the operation momentarily appeared to be headed for disaster, as one of the aircraft developed mechanical problems while hovering.
Aides feared a repeat of the infamous "Black Hawk Down" incident in Somalia in 1993, but the pilot managed to land the helicopter safely.
A firefight broke out as the Seals dashed into the compound, picking off targets as they fought their way up to the first and second floors. The courier and his brother, as well as an adult son of Bin Laden, were killed, as well as a woman being used as a human shield.
Within moments of going inside the main building, the Seals had sight of Bin Laden. He was shot in the face by one of the Seals, who fired a second shot into his head in what is known as a "double tap" and one into his chest to make sure he was dead.