Abu Yahya al-Libi, Religious Scholar
Believed to be in his late 30s, Libi has emerged as a public face of for al-Qaeda, appearing in more than a dozen lengthy Internet videos since last year.
His claim to fame is his successful escape from a high-security U.S. military prison in Bagram, Afghanistan, in July 2005, along with three other al-Qaeda members. A year later, he appeared in a 54-minute videotape dedicated to his account of his capture by Pakistani forces in 2002, his subsequent time in U.S. custody and his prison breakout.
Al-Qaeda has named Libi as a field commander in Afghanistan, though he styles himself as a theologian and has offered lengthy commentaries on a variety of political events, including the Prophet Muhammad cartoon controversy in Denmark and the criminal trials of Bulgarian nurses in Libya.
"The Libyan regime wants to cajole the West and please its masters ... by dropping the case of this heinous crime," he said in February before the Libyan government released the nurses under international pressure. They had been convicted of infecting Libyan children with the AIDS virus.
"As time has gone on, we've seen him begin to address global issues of importance to al- Qaeda," said Ben Venzke, chief executive of IntelCenter a terrorism research group. "He's become their most visible face on video, surpassing Ayman al-Zawahiri in the past year and a half, as well as their most prolific writer."
Little is known about Libi's origins. He was a member of the Libyan Islamic Fighting Group, a now defunct network that tried to topple Libyan ruler Col. Moammar al Gaddafi in the 1990s.
He spent five years as a religious student in Mauritania in the 1990s and is considered a theological scholar, although he lacks the authority to issue fatwas, or religious judgments, according to Noman Benotman, a former member of the Libyan Islamic Fighting Group who lives in London.
Michael Scheuer, a former CIA analyst and a senior fellow at the Jamestown Foundation, said Libi is seen as a "theological hardliner" who may be taking controversial stances on bin Laden's behalf.
"Abu Yahya al-Libi has been speaking directly to the hardcore faction of the Sunni Islamist movement in a way that might well be counter-productive if used by bin Laden and al-Zawahiri," Scheuer wrote last month in a paper for the Jamestown Foundation.
— Craig Whitlock and Munir Ladaa