The Nigerian suspected of trying to bring down a U.S. airliner with explosives might have used Arabic studies as a pretext for entering Yemen before disappearing for months, perhaps into one of the lawless country's al Qaeda strongholds, fellow students and teachers said.
Interviews with staff and students at the Institute for the Arabic Language this week have revealed that Umar Farouk Abdulmutallab was frequently absent from classes and spent at most one month at the school in Yemen's capital, San'a, starting in late August before vanishing. Authorities say he didn't leave the country until December and that his whereabouts during that period remains a mystery.
Adding to the notion that his studies were a ruse, one teacher at the institute said the young man stood out because he already spoke Arabic with a considerable degree of fluency.
"I noticed he understood the language very quickly and he was eloquent and convincing in his speech," Ahmed Moajjib said.
U.S. investigators have said the 23-year-old Abdulmutallab told them he received training and instructions from al Qaeda operatives in Yemen. He is accused of trying to detonate an explosive device hidden on his body as a Northwest Airlines flight carrying 289 people approached Detroit on a flight from Amsterdam on Christmas Day.
His links to Yemen have focused attention on al Qaeda's growing presence in the impoverished and lawless country on the tip of the Arabian Peninsula. Al Qaeda in the Arabian Peninsula, an offshoot of Osama bin Laden's group, claimed it was behind the attempt to bomb the flight.
Yemen's government has said Abdulmutallab spent two periods in the country, from 2004-2005 and from August to December of this year. He was enrolled at the language school during both periods to study Arabic.
Information Minister Hassan al-Lozy said on Tuesday that investigators were working on the assumption that Abdulmutallab entered the country "under the pretext of studying Arabic during his last stay."
Another teacher at the institute, Ahmed Mohammed, said Abdulmutallab spent the last 10 days of the holy month of Ramadan sequestered in a mosque and attended barely four hours of the 20-hour course he enrolled in.
On Thursday, Yemeni security officials said Abdulmutallab overstayed his visa by three months and should have been stopped by authorities from leaving the country in December. The visa was valid from Aug. 4 to Sept. 4. The language institute said he received a visa extension until Sept. 21.
Ahmed Hassan, a 28-year-old Arabic language student from Singapore who was his roommate at the institute, said Abdulmutallab spoke of wanting to also study in Yemen's eastern Hadramawt province.
Hadramawt is a remote area of barren hills and canyons that extends to vast expanses of desert to the north and the Indian Ocean to the south. It is also one of the areas of the country where al Qaeda has sought refuge, despite the government's efforts to fight the group.
In one confrontation, Yemeni security forces raided the town of Tarim in Hadramawt province in August 2008. Five militants and two Yemeni troops were killed. Those arrested included al Qaeda members who confessed to plans to attack oil facilities in Yemen and Saudi Arabia, officials said at the time.
Hassan said his roommate left the San'a institute in a hurry on Sept. 21 and didn't even say goodbye. Hassan returned to their room to find the doors open and Abdulmutallab's belongings gone.
Administrators at the school said they thought he had left the country in September.
"We arranged a taxi to take him to the airport on Sept. 21 and we said goodbye," school director Muhammad Al-Anasi told The Associated Press on Thursday. "Our responsibility toward him ended that day."
Al-Anasi was questioned in police custody for about two days before being released. In an interview with CBS News, Al-Anasi said that Abdulmutallab was friendly but not sociable and didn't have any Yemeni friends while at the school.
"He seemed happy," Al-Anasi said. "So it is a very big surprise that he did what he wanted to do."
Security officials said Thursday that Abdulmutallab didn't leave Yemen until Dec. 7 on a flight to Ethiopia. A few days later, they said, he continued on to Ghana, where he is believed to have purchased the ticket for the flight from Lagos to Detroit via Amsterdam.
The officials spoke on condition of anonymity because they were not authorized to discuss the case with the media, pending the outcome of an investigation.
The probe will look into why the Nigerian was not detained, questioned and prohibited from leaving the country by Yemen's airport authorities, they said.
Click below to watch an interview with Muhammad Al-Anasi, the founder and director of the Sana'a Insitute of the Arabic language: