ISIS Claims Beheading of British Hostage Video purports to show execution of David Haines By Newser Editors and Wire Services Posted Sep 13, 2014 5:48 PM CDT 133 comments Comments This undated file photo shows a fighter of the Islamic State group waving their flag from inside a captured government fighter jet in Raqqa, Syria. (AP Photo/Raqqa Media Center of the Islamic State group, File) (Newser) – ISIS appears to have carried out its threat to behead yet another Western hostage, this time a British citizen named David Haines. The executioner who killed Steven Sotloff in the last video had threatened that Haines would be next. Britain's foreign office said it is "working urgently" to verify the newly released video, reports the BBC. Haines, a 44-year-old aid worker, was captured in Syria last year, as were Americans Sotloff and James Foley. The video emerged a day after the family of Haines issued a public plea urging his captors to contact them. In the video, the group threatened to kill another Briton. Both British men were dressed in orange jumpsuits against an arid Syrian landscape, similar to that seen in the Foley and Sotloff videos. The SITE Intelligence Group, a US terrorism watchdog, reported the video, which was also posted online by users associated with the Islamic State group. The video was entitled "A Message to the Allies of America." Haines' purported killer, who appeared to be the same man speaking with a British accent as in the previous videos, tells the British government that its alliance with the US will only "accelerate your destruction" and will drag the British people into "another bloody and unwinnable war."