Kassig, 26, was captured on October 1, 2013, by Islamic State (IS, formerly ISIS/ISIL) militants on his way to the city of Deir Ezzour in eastern Syria.
After conversion during captivity, Kassig took the name Abdul-Rahman.
The footage reportedly shows Jihadi John murdering Kassig. This comes despite earlier reports that the extremist, who has executed other UK and US hostages, was wounded in an airstrike on a top-level extremists’ meeting in Iraq last week.
The video showing Kassig’s death is part of 15 minutes of footage, which depicts IS militants beheading several other men. The victims have been identified as officers serving under the regime of Syrian President Bashar Assad.
In the video the extremists deliver warnings to the US, UK and other countries.
Islamic State militants first showed him in the video of the beheading of UK aid worker Alan Henning, who shared a prison cell with Kassig. After Jihadi John, an IS executioner with a London accent, killed Henning, he also threatened Kassig would be next.
Kassig had served in Iraq in 2007 before becoming a medical technician. In May 2012, he travelled to Beirut, Lebanon where he volunteered in hospitals. He then helped in Palestinian refugee camps, “offering his services as a trauma medic to Syrian refugees wounded in the fighting in Syria.”
He founded his own aid organization, SERA (Special Emergency Response and Assistance), a non-governmental group intended to provide relief to Syrian refugees.
A Letter from Abdul-Rahman Kassig's Mother to IS Caliph Al Baghdadi @BintelSaif pic.twitter.com/NY4GTTiWWC
— Paula Kassig (@PaulaKassig) October 8, 2014
His parents, Ed and Paula Kassig from Indiana, had been appealing for their son’s release. They tried to reach the IS leader by writing messages on Twitter.
The Kassig family released a letter from their son written on October 13, which was delivered to them by a hostage, who had been released. In the letter Kassig thanks his parents “for everything they have both done” for him. He describes his captivity, saying that he and the other hostages “share dreams and stories of home and loved ones.”