When Mohammed Emwazi went to the mosque, a short walk north from Notting Hill and its millionaire mansions, he would sometimes run into another young Muslim from the housing projects in his neighborhood in northwest London, Bilal al-Berjawi.
Both men were part of a loose network of young Muslims in the mid-2000s, some with friendships going back to childhood, others with little more in common than a shared Arab and African heritage that set them apart from other British Muslims, most of whose families had come from Pakistan. Over time, some of the young men - Emwazi and Berjawi foremost among them - would become deeply alienated from Britain and Western society.
With the news that Emwazi is one of the most notorious members of the Islamic State - better known as Jihadi John, the hooded figure featured in many of the group's videos showing the beheadings of hostages - that loose group of young men has emerged as the latest example of a breeding ground for Islamic radicals in Europe.
The North London Boys, as the network is sometimes called, has sent dozens of young men to fight, first in Somalia and more recently in Syria. Berjawi, who trained with al-Qaida in East Africa and then rose through the ranks of al-Shabab, its Somali offshoot, was killed by a US drone strike in Somalia in 2012 after being stripped of his British citizenship. So was Berjawi's close friend, Mohamed Sakr, the older brother of one of Emwazi's classmates and friends.
The list of radicalized militants who grew up in a relatively small sliver of northwest London is striking. Two Somali men convicted of plotting to bomb the London public transport system July 21, 2005, lived within two miles of Emwazi. A onetime amateur rapper who notoriously posed in Syria with a severed head grew up just a few streets away. A man who skipped bail in 2012, went to Syria and died there a year later lived a mile away.
The militancy spawned in their neighborhoods lived on well beyond the original cause. Just as the Buttes-Chaumont group in northeastern Paris that radicalized the Charlie Hebdo killers was first energized by the Iraq War, the men in northwest London appear to have been motivated initially by a civil war in Somalia in which Islamist militants took over large areas of territory.
It is likely that Emwazi knew at least some of the other young men who, like him, left northwest London for Syria, said Shiraz Maher, a senior fellow at the International Center for the Study of Radicalization at King's College London.
"We don't know if they are connected," Maher said in an emailed comment. "There are, however, reasonable grounds to suggest that they may have known each other. Our data clearly shows that individuals who go to Syria do so in clusters, in groups of friends, and are typically from the same geographic areas."
Many questions remain about how Emwazi and others in this part of London became radicalized. Violent gang culture, often pitting Muslims against Irish and sometimes rival Sikh gangs, was not uncommon in west London in the 1990s and in some cases was a conveyor belt into jihad.
As a teenager, Berjawi was a member of such a gang, according to a study of his life by Raffaello Pantucci, a counterterrorism expert at the Royal United Services Institute. But Emwazi has no criminal record of that kind.
No central figure, like Farid Benyettou, the fiery self-taught preacher at the heart of the Buttes-Chaumont group, has so far emerged as a dominant influence among the young radicals in northwest London.
At one point, Berjawi was considered a close associate and even a deputy to Fazul Abdullah Mohammed, the head of al-Qaida's operations in East Africa, according to Pantucci's research. In the brief time between Mohammed's death and the drone strike that killed Berjawi, he had been predicted in the regional press to become the next leader. But it is not clear whether Berjawi, who was married to a British Somali and first traveled to Somalia in 2006 before al-Shabab even existed, played a role in recruiting others.
How well Emwazi and Berjawi knew each also other remains unclear. But Emwazi attended the same school as the younger brother of Berjawi's close friend. In 2009, both men booked tickets to East Africa and either traveled together or within a few months of each other. Both were stopped, both told the security services they were going on a safari vacation, and both were sent back to London. Berjawi and Sakr, also from northwest London, tried again several months later and succeeded. The pair rose through the ranks of al-Shabab until both men died in early 2012.
Court documents revealed by the BBC show that Emwazi and others were well-known to the security services.
According to another legal document from 2012 cited in the British press, they were part of "a network of United Kingdom and East African-based Islamist extremists involved in the provision of funds and equipment to Somalia for terrorism-related purposes."
Both were denied entry after coming to the attention of the security services.
Emwazi and Berjawi, and several others who later became foreign fighters, had previously complained to Cage, a British advocacy organization, about what they described as harassment at the hands of the British security services, including long detentions at airports and apparent efforts to recruit them.
In a case involving the United States, a Somali-born Briton who had also left north London for Somalia, Mahdi Hashi, was captured and detained at a U.S. base in Djibouti in August 2012. He was later taken to the United States, where he awaits trial on terrorism-related charges. He denies any links to al-Shabab and said he went to live in Somalia, partly to escape a hostile environment in Britain and partly to look after his ailing grandmother.
According to his father, Hashi was aggressively approached by the security services. They said they wanted to recruit him as an informer, but he refused. In an interview last year, his father described how agents would follow his son and call his mobile phone when he was only 16.
"He was still the age when I told him when to go to bed," said the father, who preferred not to have his full name disclosed. "He was just a child."
Once, he was present when his son's mobile rang. Hashi looked at the display and refused to answer.
"It's them again," he told his father. The next moment, his father's phone rang. When he picked up, he said a man said: "This is David from MI5, please pass me your son."
What followed, according to Hashi's father, were several years of intermittent harassment, long detentions at airports when the family traveled to Syria or Egypt for Arabic and Quran lessons, and "threatening" approaches on the street, insinuating that if Hashi did not cooperate with the services, his "life would be made hell." In Somalia, before his capture by U.S. troops, Hashi was also stripped of his British citizenship.
Researchers estimate that some 100 Britons have attempted to join al-Shabab in recent years, among them Michael Adebolajo, one of the two men who murdered the British soldier Lee Rigby on a London street. Adebolajo was also stopped on his way and sent back to Britain.
But by 2013, after the upheaval of the Arab Spring, Somalia had become less appealing as a jihadi destination, with the emergence of alternative battlefields from Syria to North Africa.
One of the first British fighters to be killed in Syria in November that year was Mohammed el-Araj, also from northwest London. He had joined the battle in Syria after being sentenced to 18 months in prison for his role in a protest outside the Israeli Embassy in London that turned violent. Some of his friends told the British news media at the time that the sentence had been too harsh and had helped radicalize him.
It was also in 2013, around the same time as Emwazi disappeared, that an amateur rapper who grew up just a few streets away left to fight in Syria. That man, Abdel-Majed Abdel Bary, is the son of Adel Abdul Bary, an Egyptian who pleaded guilty in New York last year to terrorism charges related to al-Qaida's bombings in East Africa and was Osama bin Laden's spokesman in London in the 1990s. In August last year, his son posted the notorious photo of himself with a severed head, alongside the words "Chillin' with my other homie, or what's left of him."