Qaeda number two Ayman Al-Zawahiri considered the real mastermind of the global terror franchise, is now set to succeed Osama Bin Laden as the world's most wanted man. Zawahiri has been hiding ever since the United States declared its war on terror after the September 11, 2001 attacks. The former eye surgeon's position as Bin Laden's main strategist and mentor earned the 59-year-old a $25 million bounty on his head. The US Federal Bureau of Investigation's list of most wanted terrorists said he was also Bin Laden's personal doctor. He hails from a wealthy Egyptian family. His father was a reputed physician and one of his grandfathers a prayer leader at Cairo's Al-Azhar institute, the highest authority for Muslims. He became involved with Egypt's radical Muslim community at a young age and was reportedly arrested as young as 15 for being a member of the outlawed Muslim Brotherhood, the Arab world's oldest fundamentalist group. He has published several books and studies on Islamic fundamentalism, which came for many to symbolize the radical Islamist movement. He married in 1979 and trained as a surgeon in Cairo. Zawahiri was jailed for three years in Egypt for militancy and was implicated in the 1981 assassination of president Anwar Sadat and the massacre of foreign tourists at the city of Luxor in 1997. Facing a death sentence, he left Egypt in the mid-1980s and soon he headed for Peshawar where the resistance to the Soviet occupation of Afghanistan was based. He worked as a doctor treating wounded fighters who came to take part in the war including Bin Laden. In the early 1990s Zawahiri is believed to have lived in Europe before linking up again with Bin Laden in Sudan or Afghanistan. He was arrested in 1996 in Russia after apparently trying to recruit fighters for Chechnya. In 1998 he was one of five signatories to Bin Laden's order calling for attacks against US civilians and he began appearing regularly at the Al-Qaeda leader's side. He is listed on the US government's indictment for the 1998 bombings of the US embassies in Kenya and Tanzania, and he was sentenced to death in absentia by an Egyptian court a year later. Zawahiri went into hiding after US-led and Afghan Northern Alliance forces toppled the fundamentalist Taliban in late 2001. The Taliban hosted Bin Laden and Zawahiri and refused to hand them over after 9/11.