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Westgate attack: BBC uncovers new evidence

3 October 2013 Last updated at 15:43 BST

A BBC investigation has uncovered evidence of a breakdown in control when the military entered the Westgate mall, Nairobi, during an attack by al-Shabab militants.

Meanwhile, a leaked security document has revealed the group behind the attack recruited members not just abroad, but from within Kenya itself.

Karen Allen reports from Nairobi.