At high school in Togo, Brako recalls that AbdulMutallab usually wore jeans and a T-shirt.

CNN: STORY HIGHLIGHTS

"In London he isolated himself from some of his former friends, " Kwesi Brako told CNN.

CNN: STORY HIGHLIGHTS

Brako kept up with AbdulMutallab through mutual friends in the British capital.

CNN: STORY HIGHLIGHTS

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.

CNN: STORY HIGHLIGHTS

"He was very humble, " Brako recalled.

CNN: STORY HIGHLIGHTS