(CNN) -- Umar Farouk AbdulMutallab, the 23-year-old Nigerian national who allegedly attempted to bomb a U.S. airliner over Michigan on Christmas day, became more devout about his Muslim faith while attending university in London, according to a former friend.
"In London he isolated himself from some of his former friends," Kwesi Brako told CNN. "He became much more serious about his religion."
Brako, a Christian, was in the same year as AbdulMutallab at the English boarding school they attended in the western African nation of Togo and said they were close friends. In the fall of 2005, he moved to England at the same time as AbdulMutallab to start university. But the two friends, who attended different schools, lost touch while in London.
AbdulMutallab became increasingly involved in the Islamic Society of University College London (UCL) -- one of Britain's premier universities -- quickly becoming its vice president and threw all his energies into this new role, Brako said. Brako kept up with AbdulMutallab through mutual friends in the British capital. In June 2006, AbdulMutallab became president of the UCL Islamic Society, CNN learned.
"He started wearing traditional Muslim robes with trousers rolled up around the ankles," said Brako, "Even in the winter he wore sandals."
In Britain, this style of dress is often associated with Muslims espousing a hardline-fundamentalist form of Islam. At high school in Togo, Brako recalls that AbdulMutallab usually wore jeans and a T-shirt.
AbdulMutallab never bragged about his family's wealth, which stood out even among the other well-to-do families who sent their children there. "He was very humble," Brako recalled.
AbdulMutallab was very athletic and loved playing basketball and soccer, according to Brako.
"Umar was sociable," Brako said, "but it depended on whether he was in the mood for talking."
Asked about AbdulMutallab's blog references about being lonely, Brako said that he would not have thought his friend was lonely at boarding school where he said friends formed a tight-knit community.
At high school, AbdulMutallab already stood out for his strong religious views, praying five times a day, Brako recalled.
"We nicknamed him the pope," Brako said, "because he was so religious."
At first AbdulMutallab did not like the nickname, but in time he came to accept it, said Brako.
Another nickname given to AbdulMutallab was "Alpha" -- a reference to the phrase "the Alpha and the Omega" in the Bible.
"He was the guy that never broke the rules," Brako recalled. "We all looked to him as our moral compass."
AbdulMutallab was a very cheerful person, said Brako, who did not remember him being angry.
He, however, was troubled by the American invasion of Iraq in 2003.
"Umar's view was that innocent people were suffering through no fault of their own," Brako said.
Brako remembered AbdulMutallab defending the Taliban during a classroom discussion.
"He didn't like it when others associated them with terrorism," Brako said. "What I thought he was trying to do was to stand up for his fellow Muslims. He was trying to save face for his religion."