One talk Adebolajo attended was at a community center in Woolwich -- the neighborhood where Rigby was killed -- recalled Bakri Mohammed, who noted the group met in such locations because they were not welcomed in mosques.
The vast majority of British Muslims reject the views of Bakri Mohammed -- who hasn't been allowed back in the United Kingdom since the 2005 bombings of London's transit system. His group has been barred since that time as well, though it's continued to operate under different guises. Its leaders drum home the idea that the British government is at war with Islam, but have been careful to cross legal red lines that would implicate them for inciting terrorism.
Bakri Mohammed said that, although they did not have many interactions, Adebolajo stood out because he was a new convert to the religion.
The former associate -- who was himself "born again" into Islam, but has since shed his radical views -- said that "like all of us, (Adebolajo) had a literal understanding of Islam."
Even after Bakri Mohammed left England, Adebolajo remained active in Islam circles.
British Muslim radical leader Anjem Choudary told CNN that he knew Adebolajo, noting the suspect attended demonstrations and a few lectures organized by Choudary's group Al-Muhajiroun.
In fact, an ITN video from April 2007 shows Adebolajo standing behind Choudary at a rally protesting the arrest of men who allegedly made inflammatory speeches inside a mosque.
Two or three years ago, Al-Muhajiroun leaders have said that Adebolajo moved away from the group.
The former associate -- who last saw Adebolajo in 2005 -- suspects this break might be related to this week's attack in Woolwich.
"What tends to happen is some of the group's members start to see Al-Muhajiroun as all talk and no action," he said. "So they leave the group, and then they do something."