- Dhaka attackers believed to be wealthy university students from secular background
- Profile fits a certain pattern of ISIS recruit, including "Jihadi John"
(CNN)They went to top schools and universities. They seemed like normal, middle-class men.
And on Friday, they killed 22 people in a terror attack that has left the country reeling in shock.
Bangladesh is a country depressingly used to terror -- with dozens of secular bloggers, Hindu priests and others murdered in the last 18 months -- but the July 1 attack was different, both in terms of scale, and the perpetrators.
"What's really puzzling is the background of these attackers," said Faiz Sobhan of the Dhaka-based think tank Bangladesh Enterprise Institute.
"They were normal, regular guys who hung out at cafes, played sports, had Facebook pages."
Bangladesh Information and Broadcasting minister Hassanul Haq Inna told Indian broadcaster NDTV that the attackers "were from a top school and university in Dhaka ... The parents of these boys are normal and have secular credentials."
Bangladesh is in the grips of a battle "between two terrorist groups as to who can kill more," says Sajjan Gohel, International Security Director of the Asia Pacific Foundation.
"They're competing with each other in a game of deadly one-upmanship."
The two local groups, Jamaatul Mujahideen Bangladesh (JMB) and Ansarullah Bangla Team have pledged allegiance to ISIS and al Qaeda respectively.
Bangladeshi officials have said the Dhaka attack was carried out by homegrown militants, not ISIS, and hinted towards JMB.
That is a distinction without a difference, says Gohel. "JMB are ideologically affiliated with ISIS, there's no ambiguity about it. JMB has sworn allegiance to ISIS."
Youth, wealth and education.
These are the three biggest risk factors associated with violent radicalization, according to a study by Queen Mary University in London.
Whether it is the foreign fighters who have flocked to join the group in Iraq and Syria, or homegrown attackers who pledge allegiance online, ISIS members have defied stereotypes of just who is at risk of radicalization.
While the U.S. government warned last year of impoverished young people who "have no hope for the future," many who join ISIS are often wealthy with plenty of opportunities in front of them that do not involve jihad.
Computer scientist Zeeshan ul-hassan Usmani analyzed thousands of online profiles of current and potential ISIS recruits. He told CNN last year that contrary to popular belief, recruits from Europe and the U.S. are far more likely to be educated and come from middle or upper class families.
Research by Usmani, George Washington University and the Brookings Institution has shown that more than 70% of ISIS recruits are middle class or wealthier.
They are also likely to not be particularly religious before their radicalization. Usmani found that many recruits come from secular backgrounds, learning about Islam from ISIS-linked preachers posting videos to YouTube, rather than at a local mosque.
"Capture the rebelliousness of youth, their energy and idealism, and their readiness for self-sacrifice, while fools preach 'moderation,' security and avoidance of risk," reads "The Management of Savagery," a treatise by Islamist scholar Abu Bakr Naji that has served as a playbook of sorts for ISIS.
If the Dhaka attackers did self-radicalize online, they would fit a pattern of relatively non-religious or secular ISIS recruits such as Mohammed Emzawi -- the ISIS executioner known as "Jihadi John" -- and Tahla Asmal, a 17-year-old teen whose parents had no idea he had joined the militant group until ISIS posted a photo of him online.
"There is an ideological narrative that is infecting their minds ... we have also seen this in the West," says Gohel.
"We've seen people that have what looks like a good life -- they've got jobs, families, they're well educated. It's hard to understand why they would give all this up to join a death cult."