The British jihadi being blamed for beheading US journalist James Foley may not have been responsible as the video depicting it could have been edited, experts have said.
Footage showing a masked man with a London accent delivering a warning to the West about intervening to stop Islamic State before apparently beheading Foley has triggered disgust, fear and outrage on both sides of the Atlantic.
But an expert in visual forensics, who was commissioned by The Times to examine the hideous footage, said he believed the it had been "staged" and "Jihadi John", as the Briton has been nicknamed, does not actually perform the execution.
The murderer's movement and the position of Foley's head seem to indicate it was not the moment of death.
“My feeling is that the execution may have happened after the camera was stopped,”
Aymenn al-Tamimi, a fellow at the Middle East Forum think-tank, told the paper (£).
“They show it’s an English guy because he is English-speaking for an English-speaking audience”.
He added: “It sends a message to both the UK and the US who are intervening at this stage in some way in the conflict.
"I think it sends a powerful message that it doesn’t matter where you are from, your allegiance is with the Islamic State and one day the Islamic State will encompass the entire world in terms of their thinking.”
The security services are closing in on the masked Briton and a list of potential suspects is narrowing.
A rapper from west London is a key suspect linked with the murder.
Abdel-Majed Abdel Bary left his home in Maida Vale to fight with IS in Syria, and has previously posted a picture of himself apparently holding aloft the severed head of an opponent.
London Mayor Boris Johnson has called for him to be killed, saying: "Young men such as this killer are famously told that if they die in 'battle' they will be welcomed in heaven by the sexual ministrations of 72 virgins.
"Many of them believe it - even though scholars have suggested that the reference to 'black-eyed virgins' is in fact a promise of 72 raisins.
"I suspect most of us don't give a monkey's what happens to this prat in heaven, whether he meets virgins or raisins - we just want someone to come along with a bunker buster and effect an introduction as fast as possible."