In the lurid scene of the red-handed knifeman describing his motives for hacking to death a British soldier in broad daylight, perhaps the most chilling aspect for Londoners was the man's unmistakably familiar accent.
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.
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."...It seems to me I've heard that song before...