Islamic State militants murder US aid worker Kassig

The video did not show the killing, but showed a masked man with a decapitated head. The video also appears to show a group of Syrian troops being killed.

The US national security council confirmed that it was investigating the video: “The intelligence community is working as quickly as possible to determine its authenticity.

“If confirmed, we are appalled by the brutal murder of an innocent American aid worker and we express our deepest condolences to his family and friends,” a spokesperson said.

Mr Kassig’s family said that they were aware of the video and were waiting for the US government to confirm its authenticity. In a statement, they said that they wanted their son to be “remembered for his important work and the love he shared with friends and family”.

The UK foreign office also said that it was analysing the video. “We are aware of a further video and are analysing its contents. If true this is a further disgusting murder,” a spokeswoman said.

British Prime Minister David Cameron said that he was horrified by the “cold-blooded murder”.

If confirmed, Kassig’s death would be the firth such killing of a western hostage by Islamic State militants following the deaths of two US journalists and two British aid workers.

Parents plea

Mr Kassig, 26, was captured in Syria in October 2013. He is understood to have converted to Islam while in captivity and changed his name to Abdul-Rahman Kassig.

A media blackout at the request of Kassig’s family kept his disappearance quiet until he appeared at the end of an IS video showing the murder of British aid worker Alan Henning last month.

In the video, IS militants threatened to kill Kassig. His parents later released a video pleading with the Islamic State group to release their son.

In a statement, Kassig’s parents said they understand he became a Muslim voluntarily late last year while sharing a cell with a devout Muslim.

His parents also shared a letter written by their son that was carried out by a hostage who was released earlier this year. Kassig wrote in the letter:

“I am obviously pretty scared to die but the hardest part is not knowing, wondering, hoping, and wondering if I should even hope at all.

“I am very sad that all this has happened and for what all of you back home are going through.

“If I do die, I figure that at least you and I can seek refuge and comfort in knowing that I went out as a result of trying to alleviate suffering and helping those in need.

The letter – which the parents received on 2 June – ends with the words: “I love you.”

Kassig was a former US army ranger who served in the Iraq war. He later trained as an emergency medical technician and founded the Special Emergency Response and Assistance organisation.