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.