Michael Adebolajo, 28, who was filmed wielding a bloody meat cleaver and butcher's knife as the soldier lay dead on the road behind him, was not a maladjusted immigrant like Boston bombing suspect Tamerlan Tsarnaev, but a true Londoner born and bred.
In his barrage of threats filmed after the attack, Adebolajo often sounded more like a rapper or gangster film character than an Islamist radical: "Do you think David Cameron is going to get caught in the street when we start busting our guns?" he said.
"Do you think your politicians are going to die? No. It's going to be the average guy like you and your children. So get rid of them. Tell them to bring our troops back so we can - so you can all live in peace."
He and the other suspect, who has not been named publicly, were both British citizens of Nigerian heritage.
The two men were shot by police at the scene and are now under arrest in hospital. They have not yet been charged and no lawyers have so far appeared on their behalf.
Sources familiar with the investigation say both suspects were on the radar of British police tracking Islamist extremism, but authorities had no chance to thwart an attack that required no more preparation than buying a set of butchers' knives.
Schoolmates at Marshall's Park school in the overwhelmingly white north-east London suburb of Romford that Adebolajo attended from 1996-2001, described him as a charismatic and popular kid whose transformation into a killer defied logic.
"He was always a good guy at school (who would) do anything for anyone," schoolmate Darren Marsh wrote on the Facebook page of the local newspaper, the Romford Recorder.
"He was a clever guy but he was cheeky. He acted a bit like a gangster, but I think it was just image. I'd never have seen him as a Muslim extremist."
Another schoolmate told the paper: "I know a lot can change in 10 years - but, whether or not he liked you, he'd stick up for you. I was bullied myself, and he was the one who put a stop to it."
Another, Paul Leech, wrote on Twitter: "Michael Adebolajo u make me sick, how could someone who was a laugh and nice bloke at school turn out like that. I'm ashamed to have known u."
Reuters was not able to independently verify the views of the individuals named.
British media focused on the apparent success of the Adebolajo family in Britain - another factor that sets the suspect apart from the financially struggling Tsarnaevs.
Adebolajo's father Anthony Adebolajo moved from Romford to Lincolnshire in northern England and worked as a nurse in Britain's National Health Service. British newspapers drew attention to the 365,000 pound pricetag of the two-car brick family home, which was raided by police at dawn on Thursday. Reuters was not able to contact the father.
Investigators have not found any link between the London attack and Nigeria's own Islamist insurgency, which is based in the north of that West African country. The Adebolajos were a Christian family, and their surname suggests they are members of the Yoruba community from the mainly Christian south.
Instead, the investigation is likely to focus on how a Muslim convert was radicalised at home in Britain.
Someone calling himself Abu Nusaybah, who said he knew Adebolajo, described on Twitter how he had grown more fervid in his views in recent years. He referred to him by the nickname "Mujahid" - warrior.
Anjem Choudary, the head of the banned Islamist group al-Muhajiroun, also knew Adebolajo by the name Mujahid for about a decade. He said the man had attended the group's events.
"He used to attend a few demonstrations and activities that we used to have in the past," Choudary told Reuters, adding he had not seen him for about two years. "When I knew him he was a very pleasant man, he was peaceful, unassuming and I don't think there's any reason to think he would do anything violent.
"I would not consider him to be a member of the organisation. I don't think he was intellectually affiliated, he was a contact. He used to attend some stuff.
"If you are a practising Muslim male and you want to do something, then you'll probably come across us at one time or another, so I don't think you should be surprised that he's been attending some of our activities."
Choudary did not recognise the other suspect but said he had not seen clear images of him.
Al-Muhajiroun gained notoriety for events to commemorate the September 11, 2001, attacks on the United States with leaflets that referred to the hijackers as "the Magnificent 19". Its Syrian-born founder Omar Bakri was banished from Britain in 2005.
Choudary's followers frequently channel anger at Britain's foreign policy - especially its participation in the wars in Afghanistan and Iraq over the past decade - against troops. They hold demonstrations at the funerals of British soldiers and stage burnings of the paper poppies Britons wear annually for Remembrance Day in honour of war dead.
Choudary has always maintained that al-Muhajiroun forbids its followers in Britain from carrying out attacks there under a "covenant of security" demanded of Muslims in non-Muslim lands.
"I'm not in the business of condemnation or condoning," Choudary said of the attack. "I think if anyone needs to be condemned it is the British government and their foreign policy. It's so clear that that is the cause."
British converts to Islam have been prominent in attacks and plots in the past, including Richard Reid, the "shoe bomber" who pleaded guilty to trying to blow up a transatlantic airliner in December 2001, and Jamaican-born Germaine Lindsay, one of the four suicide bombers who struck London transport in July 2005.
More recently, a man converted to Islam by Choudary, Richard Dart, pleaded guilty to terrorism charges in March. Authorities said Dart had discussed attacking Royal Wootton Bassett, a town that holds ceremonies for British troops killed abroad whose bodies are repatriated to a nearby air field.
British authorities have warned of the threat of "lone wolf" attackers - individuals or small groups who plan simple attacks on their own, who may be inspired by groups like Al Qaeda but do not need to coordinate with outsiders.
Choudary, who refused to condemn the London knife attack and said British foreign policy was to blame, nevertheless agreed that "lone wolves" were the threat.
"When you start to ban organisations from merely thought crimes and because you don't agree with what they say about foreign policy, then I don't think you should be surprised that people manifest their anger in different ways.
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