ISIS released video Saturday evening that shows the beheading of David Cawthorne Haines, a British aid worker. Haines' death comes just weeks after the execution of two American captives, James Foley and Steven Sotloff.

The gruesome video, first reported by the SITE Intelligence Group, is nearly identical to those showing Foley and Sotloff's executions. The clip begins with Haines reading a statement blaming British Prime Minister David Cameron for his death. From the video's transcript:

My name is David Cawthorne Haines. I would like to declare that I hold you, David Cameron, entirely responsible for my execution. You entered voluntarily into a coalition with the United States against the Islamic State, just as you're predecessor, Tony Blair, did. Following a trend amongst our British Prime Ministers who can't find the courage to say no to the Americans. Unfortunately, it is we, the British public, that will in the end pay the price for our Parliaments selfish decisions.

The executioner, apparently the same man who killed Sotloff and Foley, then reads a statement, calling Cameron an "obedient lapdog" who "will only drag you and your people into another bloody and unwinnable war," and pulls a knife to Haines' throat. The video then fades to black, before returning to show Haines' severed head on top of his body.

The video ends with the executioner threatening to kill a second British hostage, identified as Alen Henning: "If you, Cameron, persist in fighting the Islamic State, then you, like your master Obama, will have the blood of your people on your hands."

Cameron appeared to confirm the beheading later Saturday, calling it an "act of pure evil" in a statement.

Haines was captured in a small Syrian village in March 2013 while working with a French group to deliver humanitarian aid. His abduction had been a secret until the publication of Sotloff's execution video earlier this month.

Haines is survived by his wife, Dragana, and two daughters. On Friday, his family released a statement directed at ISIS. "We are the family of David Haines," the message said. "We have sent messages to you to which we have not received a reply. We are asking those holding David to make contact with us."