A video purporting to show the killing of US aid worker Peter Kassig by Islamic State in Syria has been posted on the internet.
The footage has not been verified.
The former soldier was threatened at the end of a video showing the beheading of British aid worker Alan Henning in October.
Mr Kassig, a 26-year-old from Indiana, was taken hostage in October 2013.
http://news.sky.com/story/1374321/vi...e-being-killed
