The rough road from carer to killer

For those with a sense of victimhood and alienation, Islamism offers a potent identity to express alienation and connect their personal story to a larger, global struggle, fuelled by television images of conflicts such as those in Palestine, Chechnya or Iraq. In this way Islam has become a symbol of protest - political or social - attracting many who feel disenfranchised or wronged by the society in which they live.

This gains greater weight when you consider that not only are a great proportion of the world's poor Muslim, the places of social exclusion in the West also have a strong ethno-religious flavour, from North Africans in Paris to South Asians in Britain and to a lesser extent, Lebanese in south-western Sydney. These groups often perceive themselves as marginalised or undervalued in their society and thereby feel a connection with the "real" poor and dispossessed Muslims in other parts of the world.

These imagined feelings of connection with the poor and dispossessed are the reasons why the middle classes of the developing world have so often been the leaders in radical groups, including terrorist operations. This is heightened when they feel a sudden drop in status on migrating to the West or are excluded from its liberal social mores.

Overseas doctors as a group are not a terrorist threat. Most make a wonderful contribution to our society. It is a quirk of immigration patterns and Western skill shortages that they have formed the bulk of the latest terrorism detainees. But the event illustrates the kind of groups that may be vulnerable to the lure of terrorism. In this case, sadly, those who were dedicated to preserving human life were transformed into the exact opposite.