CAIRO — For years, Osama bin Laden's charisma kept al-Qaida's ranks filled with zealous recruits.
But it was the strategic thinking and the organizational skills of his Egyptian right hand man that kept the terror network together after the United States invaded Afghanistan in 2001 and pushed al-Qaida out.
With bin Laden dead, Ayman al-Zawahri becomes the leading candidate for the world's top terror job. His extremist views and his readiness to use deadly violence are beyond doubt.
In a 2001 treatise, "Knights Under the Prophet's Banner," he set down the longterm strategy for the jihadi movement — to inflict "as many casualties as possible" on the Americans, while trying to establish control in a nation as a base "to launch the battle to restore the holy caliphate" of Islamic rule across the Muslim world.
The attacks on the World Trade Center and Pentagon made bin Laden the United States' Public Enemy No. 1. But he likely could never have carried them out without Zawahri. Bin Laden gave al-Qaida the charisma and money, but Zawahri brought the ideological fire, tactics and organizational skills needed to forge disparate militants into a network of cells around the world.
"Zawahri was always bin Laden's mentor. Bin Laden always looked up to him," says terrorism expert Bruce Hoffman of Georgetown University.
Perhaps even more significant than Zawahri's role before the 9/11 attacks was his task afterward, when the 2001 U.S. invasion of Afghanistan demolished al-Qaida's safe haven and scattered, killed and captured its fighters and leaders. The blow was personal as well — Zawahri's wife and at least two of their six children were killed in a U.S. airstrike in the southern Afghan city of Kandahar.
Zawahri ensured al-Qaida's survival, rebuilding al-Qaida's leadership in the Afghan-Pakistan border region and installing his allies as new lieutenants in key positions. Since then, the network inspired or had a direct hand in attacks in North Africa, Saudi Arabia, Yemen, Pakistan, the 2004 train bombings in Madrid and the 2005 transit bombings in London.
He was born June 19, 1951, the son of an upper middle class family of doctors and scholars in the Cairo suburb of Maadi. His father was a pharmacology professor at Cairo University's medical school and his grandfather, Rabia al-Zawahri, was the grand imam of Al-Azhar University, a premier center of religious study.
In the 1970s, even as he earned his medical degree as a surgeon, he was active in militant circles. He merged his own militant cell with others to form Islamic Jihad and began trying to infiltrate the military.
Then came the 1981 assassination of Egyptian President Anwar Sadat by militants from Islamic Jihad. The slaying was carried out by a different cell in the group, and Zawahri has written that he learned of the plot only hours before the assassination took place. But he was arrested along with hundreds of other militants and served three years in prison. During his imprisonment, he reportedly was tortured heavily — one factor some have cited as pushing him into a more violent radicalism.
After his release in 1984, Zawahri returned to Afghanistan and joined the Arab militants from around the Middle East who were fighting alongside the Afghans against the Soviets. He began courting bin Laden, who was becoming a heroic figure among radicals for his financial support of the mujahedeen, as well as fighting alongside them.
At the same time, Zawahri began reassembling Islamic Jihad and surrounded bin Laden with Egyptian members of Jihad such as Mohammed Atef and Saif al-Adel, who would one day play key roles in putting together the Sept. 11 attacks.
The alliance established al-Zawahri as bin Laden's deputy and soon after came the bombings of the U.S. embassies in Africa, followed by the 2000 suicide bombing of the USS Cole off the coast of Yemen, an attack Zawahri is believed to have helped organize.