A week since nearly 150 people were killed in an carefully planned attack by the Islamist group al-Shabab, the BBC has been given exclusive access to the university dormitories where the students died. The 15-hour siege at a university in Garissa, close to the border with Somalia, is one of the worst attacks on Kenyan soil by the al-Qaeda affiliate to date. Meanwhile, the Kenyan government has frozen the accounts of scores of businesses and individuals engaged in transferring money to Somalia. Karen Allen reports.