Umar Farouk Abdulmutallab came to the Sanaa Institute for the Arabic Language, whose slogan is "Arabic with authenticity," and after six weeks of spotty attendance, the school got him an exit visa and on Sept. 21 arranged for a car that took him to the airport, the school's director, Muhammed al-Anisi, told The New York Times.
"After that, we never saw him again, and apparently he did not leave Yemen," al-Anisi said. "We heard later that he may have gone to Hadramawt" -- a poor province where al-Qaida maintains a stronghold.
Now al-Anisi said he suspects Abdulmutallab, who already spoke fluent Arab when he arrived last summer, had used enrollment at the school as a pretext to legally re-enter Yemen after being recruited elsewhere by al-Qaida, the Times reported.
Abdulmutallab stayed in Yemen after his visa expired, Yemeni authorities say.
Abdulmutallab, a Nigerian, first attended the school in 2004-05, when his Arabic remained rough and he grew more and more radical, the report said. Those at the school recall the 23-year-old as a polite but unsociable man who went to mosques to pray five times a day
"I remember him as very friendly, quiet and respectful," al-Anisi said. "You would never imagine he would do this horrible thing. From smiling and helping to killing, I can't believe it."
Abdulmutallab was released from a Michigan hospital Sunday, officials said. He was charged with attempting to ignite an incendiary device aboard a Friday flight from the Netherlands to Detroit.
Notable deaths of 2014 [PHOTOS]