U.S. investigators were traveling to Yemen on Monday in search of suspects in last week's foiled bomb plot, but suspicion already has focused on a bomb-maker already suspected in a foiled attempt to bring down a Detroit-bound airliner last Christmas.
NPR has learned that officials are zeroing in on a 28-year-old Saudi bomb-maker named Ibrahim al-Asiri, a high-ranking member of the organization known as al-Qaida in the Arabian Peninsula, or AQAP.
Al-Asiri has been linked to other recent plots by the group, an offshoot of the main al-Qaida organization. He is known to be innovative, having developed the so-called underwear bomb that Umar Farouk Abdulmutallab allegedly tried to detonate aboard Northwest Airlines Flight 253.
John Pistole, the head of the Transportation Security Administration, said Monday on CBS's The Early Show that his agency had dispatched security experts to Yemen to provide training and equipment and to assist with screening cargo leaving that country.
U.S. investigators have said the mail bombs found in the United Arab Emirates and England were headed to two synagogues in Chicago. But British Home Secretary Theresa May said it was possible that the cargo plane carrying the package from Yemen may have been a target, too.
Over the weekend, the White House's top counterterrorism official, deputy national security adviser John Brennan, told Yemen's President Ali Abdallah Saleh that his country should take the lead in responding to the terrorists, a top Yemeni official told The Associated Press on condition of anonymity.
A second package was discovered in Dubai, where white powder explosives were discovered in the ink cartridge of a printer, police said in a statement. The device was rigged to an electric circuit, and a mobile phone chip was hidden inside the printer, the statement said.
"It is unclear in this case if the style of bomb has made [Al-Asiri] a prime suspect or if investigators actually found forensic evidence -- like a fingerprint or a hair -- on the bombs," NPR correspondent Dina Temple-Raston told Morning Edition.
"He's a creative guy when it comes to bomb delivery systems," she said.
The Yemen-based al-Qaida in the Arabian Peninsula has been linked to the bomb plot because of the use of the explosive PETN, which was used by the group in last Christmas Day's bombing attempt of a Detroit-bound airliner. U.S. authorities also had intelligence that Yemeni al-Qaida was planning this operation, according to a U.S. official who spoke on condition of anonymity to discuss matters of intelligence.
Two people were detained in Yemen over the weekend, but later released.
Sources tell NPR that the return address and phone number used to send the packages belonged to 22-year-old engineering student Hanan Samawi at the University of Sana'a -- in the capital of Yemen.
So authorities picked her up.
Her mother, who refused to let her be taken away to jail alone, also insisted on accompanying her, so she was detained as well.
Authorities later came to believe that someone else was using Samawi's name, Temple-Raston said.
Meanwhile, the FBI and Homeland Security Department say packages from a foreign country with no return addresses and excessive postage need to be scrutinized, according to an advisory sent to local officials around the country and obtained Monday by The Associated Press.
Despite several ill-fated U.S. airstrikes in Yemen since December 2009 that have killed civilians and a Yemeni government official instead of their intended al-Qaida targets, the government of Yemen cooperated with U.S. investigators in efforts to track down terrorists in the country.
Yemen's president, Ali Abdullah Saleh, acknowledged Saturday that his government is working with the CIA, according to a translation of his remarks by Yemen's embassy in Washington.
Even so, the failed airstrikes have made working together more difficult, according to Gregory Johnsen, who specializes in the study of Yemen at Princeton University.
Instead, it has "backfired on the U.S. and has turned out to be a recruiting field day for al-Qaida," Johnsen told Morning Edition.
As a result, Saleh has been reluctant to allow expanded use of armed drones or regular raids by U.S. special operations units on Yemeni soil, Johnsen said.
While Yemeni officials have complained bitterly about collateral damage from some of the attacks, U.S. administration officials insist the Yemeni government signs off on those missions at the highest level, as part of combined counterterrorist operations.
Those operations are coordinated from an intelligence command center the U.S. runs with the Yemenis, where it shares intelligence gathered by satellite, manned aircraft and unmanned drones -- some of which were observed last week, as reported in the Yemeni press.
But Johnsen believes that the White House hasn't taken the threat from Yemen seriously enough.
"We're almost a year out from [the Christmas bomb] ... attempt and there really hasn't been the serious intellectual grappling with diverse and numerous challenges coming out of Yemen coming out of the Obama administration, at least at this point," he said.
NPR's Dina Tample-Raston contributed to this report, which contains material from The Associated Press. [Copyright 2010 National Public Radio]