Henning, a 47-year-old from Manchester in northwest England who volunteered to help drive an aid convoy to Syria for Muslim charity Aid4Syria, was kidnapped 10 months ago.
The video released yesterday mirrored earlier ones that ISIS put out, and ends with an Islamic State fighter threatening a man they identified as an American named Peter Kassig..
The video, which emerged yesterday, shows Henning on his knees against a desert backdrop and wearing an orange prison-style outfit, with a masked militant standing over him wielding a combat knife before the video cut to his beheading.
"Obama, you have started your aerial bombardment of Shams (Syria), which keeps on striking our people, so it is only right that we continue to strike the neck of your people," the masked militant said.
The Associated Press could not immediately verify the video's authenticity, though it was released in the same manner as other ISIS group videos and the masked militant sounded similar to the one who carried out the other slayings.
British Prime Minister David Cameron confirmed waht he called the "brutal murder" of aid worker Alan Henning by the Islamic State group and vowed to bring his killers to justice.
"The brutal murder of Alan Henning by ISIL (another term for ISIS) shows just how barbaric and repulsive these terrorists are," Cameron said in a statement.
"We will do all we can to hunt down these murderers and bring them to justice," Cameron said, adding that the fact that Henning was captured and killed while trying to help others "demonstrates that there are no limits to the depravity of these ... terrorists".
This is the fourth such video released by the Islamic State group. The full beheadings are not shown in the videos, but the British-accented, English-speaking militant holds a long knife and appears to begin cutting the three men, American reporters James Foley and Steven Sotloff and British aid worker David Haines.
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