Ayman Al-Zawahiri is now at the forefront of Al-Qaeda after the US announced the killing of the militant organisation’s leader Osama Bin Laden.

Widely perceived as Bin Laden’s right hand man and the real brain behind Al-Qaeda, Al-Zawahiri is now official leader of the group.

The enigma of Al-Zawahiri is made stark by his origins. A surgeon from a well-to-do Egyptian family of prominent physicians and intellectuals, who lived in the upscale district of Maadi south of Cairo, the course of his life has taken him to the top of the world’s largest terrorist network.

Born to Mohamed Rabea Al-Zawahiri and Umayma Azzam in 1951, Ayman was the descendent of two powerful families and of a long line of important figures in Egyptian history.

Al-Zawahiri’s father and uncle were prominent professors of medicine at Cairo and Ain Shams universities, both filled high academic positions in their respective faculties. Muhamed Al-Ahmadi Al-Zawahiri, Ayman's great uncle, was in 1929 grand imam of Al-Azhar University, Egypt's renowned millennium-old Islamic educational centre.

Al-Zawahiri’s maternal grandfather, Abdel Wahab-Azzam, was a prominent professor of Oriental literature, dean of the Faculty of Literature at Cairo University and later Egypt’s ambassador to Saudi Arabia and Pakistan. At the end of his career, he established and administered Riyadh University in Saudi Arabia.

Al-Zawahiri’s great uncle, Abdel-Rahman Azzam was a notable figure in the Egyptian anti-colonial struggle, and a pioneer of pan-Arab nationalism. During World War II, he played a part in the Libyan struggle against the Fascist occupation. After the war he played a prominent role in founding the League of Arab States, of which he became the first secretary general.

Involved in Islamist politics early in life, Al-Zawahri was arrested for being a member of the Muslim Brotherhood as young as 15 years old.

Studying medicine at Cairo University, Al-Zawahiri graduated in 1974. He joined the group Islamic Jihad a year before graduating, but this did not stop him from obtaining his Masters in surgery four years later.

In 1981, Al-Zawahiri was charged of being part of the conspiracy to assassinate Egyptian President Anwar Al-Sadat. He was cleared of the charges. He spent three years in prison, however, for illegal arms possession, travelling abroad upon his release. After staying in Saudi Arabia, Al-Zawahiri travelled to Pakistan where the resistance to the Soviet occupation of Afghanistan was based, and where he was believed to have first met Bin Laden. He then moved to Afghanistan

Al-Zawahiri became an advisor to Bin Laden and also his personal physician.

In his venture to Pakistan and Afghanistan, Al-Zawahiri had taken over leadership of the militant group the Egyptian Islamic Jihad, which US intelligence believes took part in the 1998 bombings of US embassies in Dar Al-Salaam, Tanzania, and Nairobi, Kenya. The Egyptian Islamic Jihad merged with Al-Qaeda around this time.

Al-Zawahiri has a $25 million bounty on his head set by the US State Department. In recent years, Al-Zawahiri, more so than Bin Laden, became the more frequent public face of Al-Qaeda. On 8 June 2011, Al-Zawahiri released a statement saying Bin Laden would continue to "terrify" the United States after death.