Anjem Choudary, a former leader of a banned British radical group called al-Muhajiroun, said Adebolajo was a Christian who converted to Islam around 2003. Choudary told the AP that Adebolajo participated in several of the group's London demonstrations before Britain outlawed al-Muhajiroun in 2010.
Omar Bakri Muhammad, another former al-Muhajiroun leader and radical Muslim preacher, said Adebolajo is a Nigerian who was born and raised in Britain. He said Adebolajo attended his London lectures in the early 2000s, but added he had not stayed in touch with the suspect since then.
Bakri fled London and resettled in Lebanon in 2005 after suicide attacks on London's public transit system killed 56 people, including four bombers.
"I don't know what Michael did since 2004 or 2005," Bakri told the AP. "Two years ago he stopped attending our open lectures and lessons as well as our activities."
The University of Greenwich confirmed Saturday that Adebolajo was a student there from 2003 to 2005 but dropped out.
Fewer details have emerged about Adebowale besides one reported brush with death as a teenager.
The Guardian newspaper, citing police and court records, reported Saturday that Adebowale was stabbed in 2008, when a man attacked him and two friends in a London apartment. One 18-year-old friend died and the attacker received a life sentence for murder, the newspaper said.
MI5 Director-General Andrew Parker is expected to deliver a preliminary report next week to Parliament's Intelligence and Security Committee detailing what the agency knew about both suspects and whether the domestic spy agency could have done anything to stop the attack.
The directors of Britain's foreign spy agency, MI6, and Britain's eavesdropping agency, GCHQ, also are expected to give reports on what intelligence they had on the two men.
Police earlier this week detained three others in connection with the murder probe. Two women were released without charge, and a 29-year-old man has been bailed pending further questioning.