Despite the United States' superior military and reconnaissance prowess, when it came to verifying the identity of bin Laden's body, some of the methods used were decidedly old-fashioned.

According to the Washington Post, one of the ways that the Americans identified that they had indeed nabbed the al-Qaida mastermind by "measuring" him in comparison to that of a 6-foot-tall Navy SEAL.

Intelligence agencies had been tracking the Abbottabad compound where bin Laden was hiding after a tip-off in August, Bob Woodward reported in the Post, noting that a tall man would circle the mansion's courtyard daily, but never left.

American analysts reportedly had dubbed bin Laden "the pacer". Bin Laden was known to be exceptionally tall, raising the suspicions of intelligence officials; however, the imagery was never good enough to make out his face.

U.S. President Barack Obama, who witnessed the entire mission that led to the killing of the al-Qaida leader who had evaded capture for almost a decade, was informed that a Navy SEAL lay down next to bin Laden's body to ascertain his height. Bin Laden's body was slightly longer than the SEAL's, Woodward reported.

Upon learning of how bin Laden was measured, the U.S. president turned to his advisers and reportedly asked, “We donated a $60 million helicopter to this operation. Could we not afford to buy a tape measure?”

The trail to the U.S. mission that killed the al-Qaida leader began with a phone call last year to a man known as the main courier to bin Laden. The CIA was able to then trace the call, the Washington Post reported, leading them to the compound.

It started, Woodward said, when Abu Ahmed al-Kuwaiti, the code name used by U.S. intelligence to identify bin Laden's main courier, took what appeared to be an innocuous call from an old friend.

The friend then asked Kuwaiti how he was doing, to which the trusted courier responded, “I’m back with the people I was with before", the Washington Post said.

This response was reportedly extremely meaningful, implying that Kuwaiti had returned to bin Laden's inner circle. Woodward claimed this is what started U.S. intelligence on bin Laden's scent, culminating in his killing.