Islamic State defector: 'I joined out of fear'

President Barack Obama has confirmed the death of US aid worker Abdul-Rahman Kassig, whose beheading was shown in a video posted by Islamic State (IS).

But the extremists are not just accused of killing western hostages, but also Syrians and Iraqis on a massive scale.

A defector from the IS group has been speaking to the BBC's Paul Wood in Turkey, about their brutality in the Syrian towns under their control.