ITV News can confirm the British aid worker being held hostage by Islamic State is David Haines.
The 44-year-old, from Perth, Scotland, was taken by militants while working for a non-governmental organisation in Syria in March 2013.
The father-of-two was threatened in a video showing the murder of fellow captive, US journalist Steven Sotloff.
Other news organisations in the UK have also confirmed the hostage's identity.
I've been told at the Nato summit that the intelligence services know exactly who 'Jihadi John' is - or at least are 99.9% certain.
The British aid worker being held by Islamic State is David Haines, a 44-year-old father-of-two from Perth, Scotland.
In a video statement which claims to record his final words US hostage and journalist Steven Sotloff blames US foreign policy for his death.