Alan Henning's ISIS killers must be found, U.K.'s David Cameron says

Prime Minister David Cameron says the slaying of a British hostage in Syria demonstrates the necessity of destroying the Islamic State extremist group.

Cameron said the video posted Friday night, which showed Alan Henning reading an anti-Western message before his captor put a knife to his neck, demonstrated that ISIS was repulsive and beyond reason.

"There is no level of depravity to which they will not sink. No appeals made any difference," Cameron said Saturday after receiving a security briefing from Foreign Office, intelligence and military officials at Chequers, his official country retreat.

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"The murder of Alan Henning is absolutely abhorrent, it is senseless, it is completely unforgivable," Cameron said. "Anyone in any doubt about this organization can now see how truly repulsive it is, and barbaric it is as an organization.

"The fact that this was a kind, gentle, compassionate and caring man who had simply gone to help others, the fact they could murder him in the way they did, shows what we are dealing with. And this is going to be our struggle now — that with others we must do everything we can to defeat this organization."

The 47-year-old Henning, a taxi driver from the town of Eccles in northwest England, was abducted minutes after his aid convoy entered Syria in December 2013. He was the fourth hostage killed by ISIS extremists.

Before he left the U.K.. to do humanitarian work, the father of two drove a taxi in the community not far outside Manchester. His wife, Barbara, had pleaded for his release, calling her husband a "peaceful, selfless man" who wanted to help those in need.

Muslim leaders across Britain urged worshippers worldwide to pray for Henning and peace in the Middle East as they gathered at mosques to celebrate Eid al-Adha, Islam's annual "festival of sacrifice."

"Millions should be praying today for Alan Henning, a good and honourable man," said Muslim peace activist Shaukat Warraich, speaking outside a mosque in the city of Birmingham.

Egypt's Foreign Ministry denounced what it called a "barbaric and savage act that fully contradicts Islamic religion tenets and the simplest human and ethical rules."

"Alan had gone to Syria to help get aid to people of all faiths in their hour of need," Cameron said in a statement on Friday. "The fact that he was taken hostage when trying to help others and now murdered demonstrates that there are no limits to the depravity of these ... terrorists.

"We will do all we can to hunt down these murderers and bring them to justice." 

The video ended with an Islamic State fighter threatening a man identified as an American named Peter Kassig.

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Two U.S. officials, who spoke on condition of anonymity out of concerns of not having permission to release the information, confirmed that Kassig was being held by Islamic State militants. The officials declined to elaborate.

The family of the former Army Ranger from Indiana says the man moved to the Middle East to provide humanitarian aid to refugees. Kassig's parents say their son converted to Islam while in captivity and goes by the name Abdul-Rahman. They say he served in the Iraq war and became an emergency medical technician after being honourably discharged for medical reasons.
 
Kassig travelled to Lebanon in 2012 to work as a medical assistant in border hospitals. He has been held since October 2013.

"Obama, you have started your aerial bombard of Shams [Syria], which keep on striking our people, so it is only right that we strike the next of your people," a masked militant said in the video.

U.S. President Barack Obama condemned the "brutal murder" of Henning, and said the U.S. will work with U.K. allies "to bring the perpetrators of Alan's murder — as well as the murders of Jim Foley, Steven Sotloff and David Haines — to justice."

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 men.

Previous victims included American reporter James Foley, American-Israeli journalist Steven Sotloff and British aid worker David Haines.

FBI Director James Comey says American officials believe they know the identity of the masked militant, who speaks in a London accent. Comey has declined to name the man or reveal his nationality.