After the 11 September 2001 attacks on the United States, an informant revealed information to the Singapore Internal Security Department regarding Muhammad Aslam Yar Ali Khan, a Singaporean of Pakistani descent, who was a member of a group partnered with Al-Qaeda. Muhammad Aslam Yar Ali Khan was placed under surveillance by Singapore Internal Security Department, after which he left for Pakistan on 4 October. This man was captured by Afghan Northern Alliance forces in Afghanistan. His interrogation led investigators to more Jemaah Islamiah members in Singapore.