BBC World Service Service.

This is Helena Merriman with the Inquiry.

This week is part of the world service identity season.

We're asking, what kind of person becomes a violent jihadi?

On the 11th of April, a militant from the Islamist group, al-Shabaab, drove a car packed with explosives into a restaurant in the Somali capital, killing five people.

The same day, a Taliban motorbike suicide bomber drove into a bus in Afghanistan,

killing 12.

That same week, there were attacks in Syria, Niger, Pakistan and Libya, all carried out by people described

as violent jihadis.

In the aftermath of each one, a question was asked again and again.

What kind of person could do this?

It's a question that academics and intelligence analysts have been trying to answer for decades.

Are there pre-existing personality traits that make someone more likely to become a violent jahardi?

If so, it would be good to know.

In this inquiry we're going to tell the story of that search for the militant mindset.

You're going to hear from four leading researchers, people who've all interviewed dozens of militants, as we ask, what kind

of person becomes a violent jihadi? Part 1, Psychopaths?

You've got very, very different types of people that I've interviewed from failed suicide bombers to terrorist leaders,

highly committed, very, very dangerous people who have killed to people who really were completely out of their debt.

Our first expert witness Andrew Silk, a professor of criminology at the University of East London,

who's advised governments all over the world on the psychology

of terrorism, an academic field which began in the early 70s.

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