"I didn't believe what they were saying on TV because it was like 'It's not possible to be him,' until we saw him in the school uniform, which we are accustomed to. I was like, 'No, this is crazy,'" Efemena Mokedi, who attended a British preparatory school in Togo with Abdulmutallab, told CBS' "The Early Show" Monday.
Mokedi, who last saw Abdulmutallab in 2007, described him as a "great guy" and a "devoted religious person."
"He was not someone that …could have any bad qualities - just someone who was lively person [and] sociable."
Abdulmutallab's family released a statement Monday saying he had cut off contact with them and disappeared from their lives until they awoke to the attempted Christmas day.
According to the family, his father first reached out to Nigerian security forces and later to U.S. officials about his concerns that his son had not contacted him in months. U.S. authorities said that in November, Abdulmutallab's father visited the U.S. embassy in Abuja, Nigeria, to discuss his concerns about his son's religious beliefs. Abdulmutallab told U.S. officials who arrested him on the Detroit-bound airliner that he had sought extremist training at an Islamist hotbed in Yemen.
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On Dec. 24, Nigerian officials say Abdulmutallab re-entered Nigeria for only one day to board a flight in Lagos, where he walked through airport security carrying only a shoulder bag, with explosives hidden on his body.
"We were hopeful that they would find and return him home," the family said. "It was while we were waiting for the outcome of their investigation that we arose to the shocking news of that day."
Abdulmutallab is being held in a federal prison in Michigan after suffering burns in the botched bombing. U.S. authorities have said he claimed to be carrying out an attack on orders from al Qaeda.
But Mokedi, a Christian, said he would talk about religion with Abdulmutallab, a Muslim, and said the latter was not dogmatic about his faith.
And he was someone who followed the rules and "never used to indulge" in the pranks common among "immature high school kids," Mokedi said.
"He was always like the person who was the police, the mediator of all the things we were trying to … do in our dorms."
Mokedi said he believes outside influences pushed him to more extremist views.
Abdulmutallab's father, prominent banker Umaru Abdulmutallab, previously said he thought his son traveled to Yemen before the attack. Monday's statement, while not offering specifics, described how the father spoke with Nigerian security agencies about two months ago. Apparently unsatisfied by the response, the father spoke with U.S. officials a few weeks later to ask for "their assistance to find and return him home."
"We provided them with all the information required of us to enable them" to find Abdulmutallab, the family said.
A Nigerian police spokesman declined to comment, while officials with Nigeria's State Security Service could not be reached for comment Monday. A spokesman at the U.S. Embassy in Abuja, Nigeria's capital, said he had no information on the father's efforts.
The family's statement did not offer any specifics on where Abdulmutallab had been. He graduated from the well-known University College London before apparently severing ties with his family.