Ibrahim Hassan al-Asiri, considered a key figure in al-Qaida's most active franchise, is now the chief suspect behind the mail bombs sent from Yemen and bound for the United States, according to U.S. intelligence officials.
He is suspected of packing explosives into the underwear of a Nigerian accused of trying to blow up a Detroit-bound airliner last Christmas and sent his own brother on a suicide mission against a top Saudi official.
Together with a US-born preacher, Yemeni militants, and former Saudi inmates of Guantanamo, al-Asiri makes up the leadership of Al-Qaida in the Arabian Peninsula.
Forensic analysis indicates that al-Asiri, who lives in Yemen, built all three devices and is believed to have a fair degree of skill and training, although all the operations have been unsuccessful.
British Home Secretary Theresa May said the bomb discovered on the plane that landed in England was powerful enough to bring down the aircraft. A U.S. official and a British security consultant said the device, hidden in a printer cartridge, was sophisticated enough that it nearly slipped past British investigators even after they were tipped off.
Yemeni security officials said they are searching for al-Asiri, who is believed to be in Marib province. His most effective operation was the attack on top Saudi counterterrorism official Prince Mohammed bin Nayef, in which he recruited his younger brother, Abdullah, to pose as a repentant militant.
According to their father, a veteran of the Saudi military, Al-Asiri and his brother abruptly left their Mecca home three years ago. Aside from a brief phone call to say they had left the country, he never heard from them again.
With the bomb hidden in a body cavity, Abdullah approached the prince and blew himself up. The prince was only wounded. All three bombs contained a high explosive known as PETN, or pentaerythritol tetranitrate, which was also used by convicted shoe bomber Richard Reid when he tried to destroy a trans-Atlantic flight in 2001.
In a September 2009 issue of Sada al-Malahem, or Voice of Battles, an Arabic-language online magazine put out by al-Qaida in the Arabian Peninsula, al-Asiri described how he recruited his brother and they made the journey to Yemen. He said he and his friends were originally planning to go fight the Americans in Iraq, but Saudi police raided the apartment where they were hiding and arrested them.
They entered Yemen on August 1, 2006, and met with Yemeni militant Nasser al-Wahishi, who had escaped from prison just months earlier, and became the nucleus of the new al-Qaida affiliate, said the account, which could not be independently confirmed. Al-Qaida's presence in Saudi Arabia and Yemen has been distinguished by its tenacious ability to regroup after severe setbacks, having been nearly wiped out in both countries just five years ago.
The group's battered Saudi and Yemeni branches merged in January 2009 to form al-Qaida in the Arabian Peninsula under the leadership of al-Wahishi, a former aide to Osama bin Laden who staged a dramatic jail break from a Yemeni prison with 22 others in 2006. In the past year, the organization has emerged as "one of the most dangerous branches of al-Qaida," according to a U.S. assessment.
The organization calls for the overthrow of the Saudi and Yemeni governments and has carried out a string of brazen attacks against local security forces before melting away into the rugged mountains of Yemen's inhospitable hinterlands.
Heavy-handed tactics by the Yemeni military have often only further inflamed tribal animosity. Yemen is also wracked by a number of rebellions and secessionist movements, including one throughout much of the south that has provided fertile ground to al-Qaida's recruiting efforts.