Osama Bin Laden: How al-Qaeda leader gave CIA the slip in 2001

Following the fall of Kabul in 2001, the Taliban fled the capital and headed for the mountains.

Among them was Osama Bin Laden, the world's most wanted man following the 9/11 attacks in New York and Washington earlier that year.

The CIA's Gary Berntsen was determined to catch him. Berntsen and a handful of CIA agents, together with Afghan forces, followed Bin Laden to the Tora Bora mountains.

Although air power and ground forces were used against him, the al-Qaeda leader managed to slip away.

Ten years later he was killed in a separate CIA-led operation in neighbouring Pakistan.

Gary Berntsen told Witness what happened on that mission in December 2001.

Witness is a World Service programme of the stories of our times told by the people who were there.