“Sometimes people with the worst pasts create the best futures,” reads the slogan, emblazoned on an image of a masked fighter wielding a Kalashnikov, walking into blinding light.
The poster was shared on Facebook by Rayat al-Tawheed, a group of British Isis fighters from London calling themselves the “Banner of God”.
Their target is young men looking for redemption from crime, drugs or gangs, willing to save their souls by waging jihad for the so-called Islamic State.
For all of its professed piousness, new research shows that the majority of the terrorist group’s recruits have criminal histories – an unprecedented figure for former Islamist movements emphasising purity and scholarly knowledge.
A report by the International Centre for the Study of Radicalisation (ICSR) shows that criminal and terrorist networks across Europe are merging to create a dangerous brand of jihadi for whom violence is not just a holy pursuit, but a way of life.
Professor Peter Neumann, director of the ICSR at King’s College London, said the new “crime-terror nexus” was making radicalisation harder to spot for European security services.
“A lot of analysts continue saying terrorists are middle or upper-class, Osama bin Laden was the son of a millionaire and the 9/11 attackers were students for instance,” he told The Independent.
“But I don’t think that doesn’t reflect the reality we have with Isis – we need to rethink our strategy.”
Mr Neumann said many security services still expect radicalised young men to change their behaviour and act “religiously”, perhaps by growing a beard or changing their clothing.
For some the pattern is still seen, but in many cases it is not, with several European fighters in the ICSR’s database continuing to smoke, drink and even take drugs up until their departure for the so-called Islamic State.
Similarly, criminality does not always stop with a commitment to jihad. Said Kouachi may have used funds from selling counterfeit trainers to buy the weapons he and his brother used to carry out the Charlie Hebdo massacre, while the Paris and Brussels “supercell” used their connections in the criminal underworld to manufacture the fake documents that would let them evade security services.
Mr Neumann said that of the jihadis examined for the study, two thirds had not just a criminal history but a violent history. In European countries where the figure is known, more than half of Isis fighters were previously known to the police.
“It gives criminals a moral justification for doing what they have always been doing – only now they will go to heaven,” Mr Neumann added.
Isis’ ideology puts less emphasis on theological knowledge and more on absolute obedience to its own interpretation, with the majority of recruits listed in leaked registration forms tellingly describing their Sharia knowledge as “basic”.
Where al-Qaeda “practically published a book” to justify each of its terror attacks, Isis issues a few paragraphs at most, preferring to reach its audience through glossy magazines and slick videos.
“There is now a perfect fit between these young men and a group that has shed any attempt at serious theological discourse,” Mr Neumann said.
“It’s almost thriving on the rejection of mainstream and even Salafi scholars.
“It basically says ‘you can come in if you sign up to the mission, we don’t care if you know true Islam – we are true Islam’.”
The terror group also aims to portray membership as a route to action, adventure, power and the sense of brotherhood desired by frequently vulnerable recruits searching for purpose and belonging.
Alain Grignard, a senior member of Belgium’s counter-terror agency, said Isis can be seen as an extension of inner-city crime for many European members.
“Young Muslim men with a history of social and criminal delinquency are joining up with the Islamic State as part of a sort of ‘super-gang’,” he told the Combating Terrorism Centre.
“Previously we were mostly dealing with ‘radical Islamists’ – individuals radicalised toward violence by an extremist interpretation of Islam – but now we’re increasingly dealing with what are best described as ‘Islamised radicals’.”
The link is being reinforced by what has been dubbed the “gameification of jihad”, with Isis styling its gory propaganda videos like first-person-shooter console games, complete with graphics, crosshair views and even chilling recreations of maze challenges.
The method of recruitment is seeing radicalisation speed up, with the process commonly happening in weeks or months for the vast majority of Isis militants, compared to months of years for groups like al-Qaeda and the Taliban.
“In many cases in the past, someone might become a student activist and start supporting the jihadi ideology but then it would be a huge hurdle to convince that person to vary out a violent attack and kill somebody,” Mr Neumann said.
“But with these criminals they are already used to violence, so for the jump from being an extremist to being a violent extremist is much smaller.”
One example is Copenhagen gunman Omar el-Hussein, who killed two victims in a shooting spree after pledging allegiance to Isis in February 2015.
He had joined a gang as a teenager and was involved in burglaries, petty crime and drugs, before being jailed for a stabbing in 2013. During his prison sentence, he became extremely religious and started expressing a wish to fight in Syria, but three radicalisation alerts to authorities went unanswered.
Upon release, el-Hussein found himself homeless and jobless, carrying out his terror attack two weeks after being freed.
Isis also attracts troubled young men through what analysts describe as a “redemption narrative”, with the commitment to martyrdom portrayed as a whitewash for all past sins.
“Often there is a traumatic experience that acts as a wake-up call - sometimes a prison sentence, sometimes a friend being killed, in one case a brother’s diagnosis with cancer,” Mr Neumann said.
“They think: 'What am I doing? How do I redeem myself?' At that point they may already have a tenuous connection with jihadis. It’s a very common narrative.”
The case for jihad is often made in prisons across Europe, where a well-documented phenomenon has seen inmates radicalised and even form terror cells on the inside.
He found himself in a Bremen jail with René Marc Sepac, an al-Qaeda-linked radical jailed for spreading jihadist propaganda, who changed his “whole understanding of Islam”.
Sarfo travelled to Syria to fight for Isis last year but defected from the group after three months and returned to Germany, where he remains in prison.
Mr Neumann said the ICSR’s report had documented several cases where prison authorities had been unaware of radicalisation, or had their alerts ignored by counter-terror agencies.
One of the most prominent examples is the network that carried out both the Paris and Brussels attacks.
Co-ordinator Abdelhamid Abaaoud, bomber Ibrahim Abdeslam and his brother Salah, were all involved in crime in the Brussels suburb of Molenbeek – with Abdelhamid and Salah jailed together in 2010.
Amedy Coulibaly, who would go on to kill four people at a kosher supermarket in Paris, served time for receiving stolen goods, drug trafficking, and robbery.
While inside the Fleury-Mérogis Prison, which is infamous for fostering jihadis, he told Le Monde: “Prison is the best f***ing school of crime. In the same walk, you can meet Corsicans, Basques, Muslims, robbers, small-time drug dealers, big traffickers, murderers…you learn from years of experience.”
The ICSR is calling for reform in jails across Europe to ensure that staff are trained to spot the early signs of radicalisation, while being able to effectively share warnings with security services, and make it more difficult for extremist networks to form.
Another key step to crush the “crime-terror nexus” is ensuring that mainstream imams are available for Muslim prisoners, rather than allowing radicals to volunteer to lead prayers.
“The UK is trying but there still needs to be improvement,” Mr Neumann said. “Some prisons in France and Belgium have simply lost control.”
Other steps recommended in the ICSR’s report include increased information sharing between security services, including police, customs and intelligence services, with acknowledgement of the link between criminal proceeds and terror plots.
A spokesperson for the British Government said police, security and intelligence agencies in the UK “collaborate extensively” to prevent terror attacks through sharing information and joint operations.
“We have a wide range of powers at our disposal to disrupt travel to conflict zones and manage the risk posed by returnees, including powers to temporarily seize passports and to make Schedule 7 stops at ports or airports as well as arrest and prosecution,” she added.
“Everyone who returns from Syria or Iraq can expect to be subject to investigation to determine if they pose a threat and they should be in no doubt we will take the strongest possible action to protect our national security.”
In August, the Ministry of Justice announced plans to hold extremist prisoners in specialist units, with work on the proposals still underway.
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies