Mail bomb investigators push on with Yemen man hunt

Their first suspect in custody, Yemeni police continued to search for the terrorists believed responsible for mailing a pair of powerful bombs to attack the United States. U.S. and Yemeni officials were increasingly seeing al-Qaida's hand in the failed plot.

Yemeni police arrested a young woman who was a medical student on suspicion of mailing a pair of bombs powerful enough to take down airplanes, officials said Sunday. They also detained her mother.

Investigators were hunting the impoverished Mideast country for more conspirators. U.S. officials included in that group the same bombmaker suspected of designing the explosive for a failed bombing on a Detroit-bound airliner last Christmas.

Authorities were also looking at two language institutions the plotters may have been associated with.

The explosives, addressed to Chicago-area synagogues, were pulled off airplanes in England and the United Arab Emirates early Friday morning, touching off a tense search for other devices. More details emerged Saturday about the plot that exploited security gaps in the worldwide shipping system.

British Prime Minister David Cameron said he believes the explosive device found in central England was intended to detonate on the plane, while British Home Secretary Theresa May said the bomb was powerful enough to take down the aircraft. A U.S. official said the second device found in Dubai was thought to be similarly potent.

But it still wasn't clear whether the bombs, which officials said were wired to cell phones, timers and power supplies, could have been detonated remotely while the planes were in the air, or when the packages were halfway around the world in the U.S. Still, the fact that they made it onto airplanes showed that nearly a decade since the Sept. 11, 2001 attacks, terrorists continue to probe and find security vulnerabilities.

Yemeni President Ali Abdullah Saleh told reporters that the United States and United Arab Emirates had provided intelligence that helped identify the woman suspected of mailing the packages.

A Yemeni security official said the young woman was a medical student and that her mother also was detained, but officials pointed to additional suspects believed to have used forged documents and ID cards. One member of Yemen's anti-terrorism unit said the other suspects had been tied to al-Qaida.

Yemeni and U.S. officials spoke on condition of anonymity to discuss the ongoing investigation unfolding on three continents.

Al-Qaida's Yemen branch, known as al-Qaida in the Arabian Peninsula, took credit for the failed bomb last Christmas that used PETN, an industrial explosive that was also in the mail bombs found Friday.

The suspected bombmaker behind the Christmas Day attack, Ibrahim Hassan al-Asiri, is also the prime suspect in the mail bomb plot, several U.S. officials said. Al-Asiri also helped make another PETN device for a failed suicide attempt against a top Saudi counterterrorism official last year. The official survived, but his attacker died in the blast.

The U.S. was already on the lookout for a mail bomb plot after learning terrorists in Yemen were interested in "exploring an operation involving cargo planes," a U.S. counterterrorism official said.

U.S. authorities then acted quickly after receiving a tip "that suspicious packages may be en route to the U.S" - specifically Chicago - the official said, speaking on condition of anonymity to discuss intelligence matters.

Sullivan reported from Washington. Matt Apuzzo, Adam Goldman and Kimberly Dozier in Washington, Raphael G. Satter in London, Adam Schreck in Dubai and Carla K. Johnson and Karen Hawkins in Chicago contributed to this report.