bushy beard advertised his deep attachment to the Afghan Taliban. After the September 11 attacks in the United States, the Federal Investigation Agency (FIA) launched a criminal investigation against him, leveling charges of unauthorized travel to Afghanistan. Director of the Central Intelligence Agency, George Tenet, later described intelligence reports of his meeting with Al Qaeda as "frustratingly vague." When asked by Pakistani and American investigators about the nature of Ummah Tameer-e-Nau's (UTN) work and discussions, Mahmood said that he had nothing to do with the al-Qaeda and was only working on humanitarian issues like food, health and education. Investigators from Inter-Services Intelligence (ISI) and the Central Intelligence Agency (CIA) were astonished and surprised at the extent of his nuclear weapons knowledge. During his debriefing, his son Dr. Asim Mahmood, a family medicine doctor, told ISI officials that: My father [Mahmood] did meet with Osama bin Laden and Osama Bin Laden seemed interested in that matter but my father showed no interest in the matter as he met him for food, water and healthcare matters on which his charity was working. The FIA criminal probe continued for four months and yielded no concrete results. Pressure from Pakistani society and court inquiries against the FIA's criminal probe led to Mahmood's release in 2001. His family did confirm his release but had been constantly under surveillance by the FIA; his name was placed on the "Exit Control Lists" so he is not allowed to travel out of Pakistan. Since his release, Mahmood has been out of the public eye and lives a quiet life in Islamabad, devoting most of his time to writing books and doing research work on Islam and science. Dr. Bashir Syed, former president of the Association of Pakistani Scientists and Engineers of North America (APSENA), said: "I know both of these persons and can tell you there is not an iota of truth that both these respected scientists and friends will do anything to harm the interest of their own country." Mahmood-Hoodbhoy debates Mahmood has written over fifteen books, the most well-known being "The Mechanics of Doomsday and Life After Death", which is an analysis of the events leading to doomsday in light of scientific theories and Quranic knowledge. However, his scientific arguments and theories have been challenged by some prominent scientists in Pakistan. His religiosity and eccentricity began troubling the Pakistan Physics Society; his peers often quoted him