The British aid worker named David Haines appears to have been executed by the ISIS militants, linking it to the video  posted Saturday in a website associated with the group, making the no. of Western captive to be killed third by the Islamist extremist group in recent weeks.

The ISIS video post showing Haines' apparent beheading called his execution "a message to the allies of America." 

It is produced very similarly to the video which showed the executions of American journalists James Foley and Steven Sotloff, the last of which included Haines and the threat that he'd be killed next.
The new video pictures a masked ISIS militant placing his hand on another captive, whom he identified as Alan Henning, a British citizen.
News of the gruesome killing is said to come the same day that Haines' family released a brief message to his captors through the British Foreign Office.
In it, the family says, "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."
A logistics and security manager for the Paris-based Agency for Technical Cooperation and Development, a nongovernmental humanitarian agency, the 44-year-old Haines was abducted in March 2013 near a refugee camp in Atmeh, Syria.
At that time, Haines was working to arrange for the delivery of humanitarian aid to people staying at the camp. He had previously worked on aid operations for victims of conflict in the Balkans, African and other parts of the Middle East, according to an ACTED spokesman.