The British Isil killer known as "Jihadi John" may have a body double, according to a new video analysis, which also suggests that US aid worker Peter Abdul-Rahman Kassig was beaten before his death.
Analysts who have conducted close-up examinations of the footage of Mr Kassig's severed head say the hostage's face shows a large bruise above his left eye, suggesting he put up a struggle.
Freeze-frame analysis also reveals that while there appears to be 18 or 19 jihadists and victims in the main part of the video, there are in fact 22.
As well as "Jihadi John", who plays the central role, one other is wearing a balaclava, a fact that seems to be deliberately hidden as it is visible only from a single "screen grab".
That has led the analysts to speculate that he might be intended to be a double for the chief executioner, perhaps to confuse drone surveillance.
"It could be a body double or a decoy," said Veryan Khan, the editorial director with the Terrorism Research and Analysis Consortium, which examined the video for Quilliam, a UK anti-extremist think-tank. (© Daily Telegraph, London)