Alan Henning 'killed by Islamic State': US evaluating video

A video purporting to show UK hostage Alan Henning being beheaded has been released by Islamic State militants.

The Salford taxi driver was delivering aid to Syria in December when he was kidnapped and then held hostage by IS.

IS threatened to kill him in footage last month showing the death of Briton David Haines, and in this video they threaten US aid worker Peter Kassig.

US Homeland Security Adviser Lisa Monaco said this was "another very clear example of the brutality of this group".