Via NY Times:

Two Syrian activists who used video and social media to expose human rights abuses committed by the Islamic State were tracked down by jihadists and killed in their home in a southern Turkish city, according to their colleagues.

The Islamic State, also known as ISIS or ISIL, released a graphic video claiming responsibility for their deaths on Sunday. The clip showed the body of one of the activists, his throat slit, along with a warning to the group’s opponents.

“You will never be safe from the blade of the Islamic State, and our hand will reach you wherever you are to slit your throat,” it said.

One of the men, Ibrahim Abdel Qader, was a co-founder of Raqqa Is Being Slaughtered Silently, a group of citizen journalists and human rights activists that uses social media to document abuses committed by the jihadist group in Raqqa, the Syrian city it uses as its headquarters. The citizen-journalists are a primary source about life inside the ISIS capital.

The video posted by ISIS on Sunday included a mocking reference to the group’s name, saying that the killing of the two men was meant “to teach every apostate that he will slaughtered silently.” And it raised troubling questions about the group’s potential reach into nearby countries.

Abu Ibrahim al-Raqqawi, a spokesman for the activist group, said that Mr. Abdel Qader had been stabbed more than 50 times and then beheaded in his apartment in Sanliurfa, Turkey, while Mr. Hammadi’s throat was slit.