What do we know about James Foley's killer?
The beheading of US journalist James Foley has caused shock and revulsion. But how much do we know so far about the circumstances surrounding his death?
What information do we have about his killer?
Very little. There is a virtual communications blackout from UK government on what it knows as it tries to assess the situation.
The basic facts are that the video released by self-styled "Islamic State" fighters shows a man killing American journalist James Foley. The masked man in the video speaks with a British accent - assuming that the voice has not been dubbed over from another source.
Some experts think the accent sounds like the man comes from London, as it is a mixture of multicultural speech patterns often heard on the streets of the city. However, that may be speculation given that the individual could have tried to deliberately change the way he speaks for the purposes of the video.
It has been reported that the man in the video may have been nicknamed John - one of three British men dubbed "The Beatles" - John, Paul and Ringo. It's not at all clear whether this is true, who gave them this name and whether it is widely recognised among those they are fighting with in Syria.
What do we know about the investigation?
The FBI is leading the international investigation to discover the killer, although it seems very unlikely he could be brought to justice any time soon.
Scotland Yard is examining the content of the video, but the lead agency in the UK is MI5. Officers there, alongside their colleagues in the other arms of the security services, will be analysing a huge amount of intelligence held on databases to try to find a match to the man in the video - albeit with very little to go on.
Three elements of the investigation will be paramount:
- Forensic experts will be looking at the terrain in the video to establish the location
- Technologists will be trying to establish how it reached the internet - and what they can learn from that
- Forensic experts will investigate the masked individual's physique, eyes, mannerisms and voice for clues
All of this information, alongside general intelligence about the movements of foreign fighters, will build up a picture - but it may not be conclusive.
On the other hand, security services may already have a good idea of who the individual is but are not saying. We may never know.
What do we know about British fighters in Syria?
It is very difficult to say for certain how many people have gone to fight but security chiefs think that it may be about 500. However, some community sources think that is a massive under-estimate. In short, nobody can say - but there is a lot of information out there because many fighters have done little to hide their activities.
They see social media as a means of publicising their activity in the hope of recruiting others. Some British fighters have appeared openly online, including Portsmouth man Ifthekar Jaman, now believed dead.
Others have appeared masked - but their regular postings referring to the UK, including videos in which they speak, demonstrate a connection to Britain.