Published: 19:00, 21 August 2014
| Updated: 19:20, 21 August 2014
Speech analysis of the video showing a British jihadi murdering American journalist James Foley has concluded he could be from Kent.
The masked jihadi who beheaded James Foley speaks with a southeastern English accent, and intelligence experts have narrowed it down to east London, Kent or Essex.
Speech patterns and accent are a major part of the investigation to unmask the killer, whose black outfit conceals his face and any other easily recognisable features.
Guardian journalist Martin Chulov told Sky News the man could possible be called John, and may be the same Islamic State militant who has 'negotiated' with hostages' families in the past.
In the video the masked murderer is seen standing next to Mr Foley while he is forced to blame the US for his murder.
The killer is then seen taking a knife to Mr Foley's throat before the video fades out.
Mr Foley went missing in Syria in November 2012.
"We have never been prouder of our son Jim. He gave his life trying to expose the world to the suffering of the Syrian people." - Diane Foley
His mother Diane Foley released a statement earlier this week describing him as "an extraordinary son, brother, journalist and person."
She said: "We implore the kidnappers to spare the lives of the remaining hostages. Like Jim, they are innocents. They have no control over American government policy in Iraq, Syria or anywhere in the world.
"We have never been prouder of our son Jim. He gave his life trying to expose the world to the suffering of the Syrian people."
The vast majority of media outlets have not broadcast the video, and people are being encouraged not to share it via social media.
Every morning at 10am we play you an hour of tunes from the 90s. We call it, #WeLoveThe90s.
Play 'Say It' with Garry and Laura on kmfm Breakfast and you could win £1,000!
Wake up to kmfm Breakfast with Garry and Laura - it's Kent's alarm call.