Educated young Tunisians are signing up to join Isis

Sitting in a busy Tunis café, sipping an espresso and wearing a neat button-down dress shirt, the brother of Jabeur Khachnaoui, one of two men who killed 21 tourists at the Bardo Museum in March, compares Jabeur to Nazi war criminal Adolf Eichmann, who insisted he was only following orders. "It's so horrible and so ironic, as my brother was dragged into this stuff, and I am writing my doctoral thesis on religious tolerance," says the PhD student of philosophy who asked Newsweek not to use his real name and to identify him as Mohammed. "The day he died, I was marching in a rally against terrorism."

The brothers grew up in the countryside, sons of a prosperous olive farmer. Jabeur, the youngest, often felt isolated because his siblings were so much older, recalls Mohammed. And yet he was happy and got good grades.

"There was not much to do in our village, so my guess is that when the Islamists approached him with a new vision of how to live his life, he was ripe," says Mohammed.

His family noticed a gradual change in Jabeur. He began to spend hours praying. He stopped touching women's hands to shake them, even relatives. He sometimes stayed up all night studying the Koran and had memorised nearly half of it. Mohammed, sensing something was wrong, began giving his little brother books he hoped would counteract extremist tendencies. "I don't mind that he was religious – not one bit. But I did not want him to be fanatical."

At one point, Jabeur disappeared for two months. His brother believes this is when he underwent military training.

Jabeur Khachnaoui was only 18 when he and 27-year-old Yassine Laabidi, armed with assault rifles, entered the lightly guarded museum to hunt down and kill tourists from Germany, Italy, France, Spain, Poland and elsewhere. The attackers were finally gunned down by Tunisia's elite BAT squad.

Like most Tunisians, Mohammed was watching the news on TV when authorities released the names of the killers. He later saw a photograph of the bodies of his brother and Laabidi in a pool of blood.

"I really don't understand," says Mohammed. "I just don't understand."

Many in Tunisia are trying to understand why so many young men from this relatively advanced and secular country, which emerged from the Arab Spring with a fledgling democracy, are turning to extremism and joining Isis. Tunisia sends the largest number of foreign jihadis to fight for Isis in Syria. The Ministry of Interior estimates the number to be around 3,000.

Before that museum attack in March, it was easy for many Tunisians to ignore that statistic. Tunisia is a popular holiday destination, only 965km from Italy. It has an educated, multilingual population. Each week, cruise ships from Europe would disgorge hundreds of tourists eager to see its priceless antiquities.

Now, visitors walking through the Bardo can see bullet holes in a cabinet that holds a statue of the Roman god of wine, Bacchus. The attack was not just a blow to tourism, one of Tunisia's biggest sources of revenue. It forced Tunisians to address growing radicalisation in their society.

Said (not his real name), a 25-year-old engineering student, counts nine friends, all graduates, fighting in Syria. He says most of them dismissed reports that Isis was committing horrific crimes, such as beheading people and kidnapping minorities.

"They said it was Western propaganda against Muslims. Each of them has a different reason [for going]," Said says. "Some have been tricked – they are told what an amazing life they will have in Raqqa [the Isis capital], that there are pretty women to marry, that life will be easier and they will be successful."

He pauses. "Then they get there and it's living hell. I can't say any of them were particularly religious before they went. Because of the pressure of their lives here – no jobs, no prospects – religion became a refuge, a solace."

He says money can be a factor. "It's said that some battalions do pay. I have heard up to $1,000 a month."

Tunisia's official unemployment rate is 15%, but Said Ferjani, a senior official of the Ennahda Party (a moderate Islamic party that is part of the government's coalition) says it is probably closer to 20 to 25%. The African Development Bank in Tunis puts unemployment among the young at 34%. "Something is very wrong," he says. "People have high expectations. They want a better life. So a recruiter comes around and tells them about a better life fighting in Iraq and Syria – and they accept."

An economist by training, Ferjani says that in order to absorb the 80,000 new university graduates each year – Tunisia has one of the highest rates of education in the Middle East – a minimum of 100,000 jobs need to be created. Corruption is also a problem. "But to stop corruption, you need to change the mindset," says Ferjani. "We made a new constitution – that's beautiful. But we are working with an old set of laws."

Tunisia is in transition, says Ferjani. "Everything is not rosy. There is disillusionment. When you are disillusioned, you are drawn to radicalism."

One day in late May, I meet a bearded, tattooed rapper named Da Costa in a park near the Bardo. Da Costa tells me about his brother, Yusuf, who died fighting in Syria in 2012.

"He was only 24 years old. By the time he left for Syria, he was so indoctrinated that I couldn't even talk to him. He was so brainwashed. He just kept going to the mosque, and the recruiters know exactly who is vulnerable, seeking a new life, in despair."

"I try to tell them, through rapping, not to go," Da Costa says, writing down the lyrics of one of his raps: "Brothers, do not follow the jihad. They promise you heaven when heaven is not theirs to give." He sighs. "But it doesn't work. There were so many boys from my neighbourhood who went to Syria that they actually named a battalion after it."

In Yassine Laabidi's middle-class home in the Omrane al Alaa neighborhood in Tunis, his family is still in shock, months after he attacked the Bardo Museum. They insist there were no signs Laabidi was being indoctrinated.

But Laabidi was, in fact, part of a sleeper cell activated after the 2011 Jasmine Revolution. Last December, he told the family he had to go work for a few months near Sfax, another Tunisian city. It was then, officials believe, that Laabidi trained for five months in a military camp in Libya.

The morning of 18 March, "up until the last minute, when we walked out the door that morning, [Laabidi] acted normally," his sister says. He said he was going to a Turkish bathhouse. Instead, he went out to slaughter tourists. "My son was the victim of brainwashing," Laabidi's mother says.

Ghazi Mirabet is a lawyer who has represented several "normal" young men who became jihadis fighting in Syria. "It always starts at a mosque," he says. Among Mirabet's ex clients is a famous rapper called Emino, now a prominent Isis member who posts freely on Facebook. Emino came from a well-educated, middle-class family – his mother is a civil servant in the Tunisian government. He has not contacted his mother or his lawyer since he went to Syria.

"First he used to sing about sex and drugs," says Mirabet. "Then he goes to prison for having weed. In prison, little by little, he became more religious. He stopped rapping. He stopped shaving. He grew his beard. He spent more time at the mosque. Then one day, he was indoctrinated."

The entire process to create a jihadi took about six to nine months, says Mirabet. "Terrifying, isn't it?"