Islamic State militants released a video Saturday showing the beheading of aid worker David Haines, the latest in a disturbing series of such executions.
The 44-year-old Haines, who was British, was abducted in Syria in 2013 while working for an international aid agency. His whereabouts had been unknown.
The British government had kept the kidnapping secret out of concern for his safety until another video was recently released by Islamic State, also known as ISIS or ISIL.
ISIS' video identified him as a captive, showing him in an orange jumpsuit and calling out Prime Minister David Cameron personally for his soon-to-be beheading.
The British Foreign Office had said late Saturday that it was "working urgently to verify the video," but Cameron's statement left little room for ambiguity:
"The murder of David Haines is an act of pure evil. My heart goes out to his family who have shown extraordinary courage and fortitude."