After a year locked up in Uganda with self-confessed Islamist militants, a Kenyan human rights lawyer is able to give clues as to what drove those behind Kenya's deadly mall siege, writes the BBC's Will Ross.
"They have a conviction that what they are doing is right and the rest are wrong," says Al Amin Kimathi about the members of the Somali group al-Shabab who bombed bars in the Ugandan capital, Kampala, where patrons were watching the 2010 World Cup final on TV.