All wars are vicious, but the civil war in Syria seems every day to set new standards for brutality. As the fighting rages in its third year, increasing numbers of atrocities are committed by soldiers and fighters from forces loyal to the regime of President Bashar Assad, as well as armed rebels and Islamic militants from the numerous, loosely aligned groups opposing Assad. The violence is frequently sectarian in nature, with fighters claiming they act in defense of their faith, be it Sunni, Alawite, Shiite or any of the other sects that contribute to Syria's religious landscape.
The perpetrators of atrocities themselves often use digital cameras or smartphones to photograph or film their acts of torture and murder, uploading the images to the Internet. These images and videos are used for propaganda, and their authenticity is often impossible to verify. It is very rare that a group of fighters from either side gives a professional photojournalist from a country outside Syria full and unfettered access to chronicle an atrocity as it unfolds. The images above are products of that access.
What follows is a harrowing series of photographs of Islamic militants publicly executing, by decapitation, a young Syrian in the town of Keferghan, near Aleppo, on August 31, 2013.
Because of the danger in reporting inside Syria, it was not possible to confirm the identity or political affiliation of the victim. Nor are we certain about the motivation of his killers. One eyewitness who lives in the area and was contacted by TIME a week after the beheadings said that the executioners were from ISIS, an Al-Qaeda franchise operating in Syria and Iraq.
TIME obtained the images exclusively from a photographer who was recently in Syria. This decapitation was the last of four executions he documented that day. TIME has agreed not to publish the photographer’s name, to protect him from repercussions when he returns to Syria. What follows is an edited account of his experience:
The man was brought in to the square. His eyes were blindfolded. I began shooting pictures, one after the other. It was to be the fourth execution that day I would photograph. I was feeling awful; several times I had been on the verge of throwing up. But I kept it under control because as a journalist I knew I had to document this, as I had the three previous beheadings I had photographed that day, in three other locations outside Aleppo.
The crowd began cheering. Everyone was happy. I knew that if I tried to intervene I would be taken away, and that the executions would go ahead. I knew that I wouldn’t be able to change what was happening and I might put myself in danger.
I saw a scene of utter cruelty: a human being treated in a way that no human being should ever be treated. But it seems to me that in two and a half years, the war has degraded people’s humanity. On this day the people at the execution had no control over their feelings, their desires, their anger. It was impossible to stop them.
I don’t know how old the victim was but he was young. He was forced to his knees. The rebels around him read out his crimes from a sheet of paper. They stood around him. The young man was on his knees on the ground, his hands tied. He seemed frozen.
Two rebels whispered something into his ear and the young man replied in an innocent and sad manner, but I couldn’t understand what he said because I don’t speak Arabic.
At the moment of execution the rebels grasped his throat. The young man put up a struggle. Three or four rebels pinned him down. The man tried to protect his throat with his hands, which were still tied together. He tried to resist but they were stronger than he was and they cut his throat. They raised his head into the air. People waved their guns and cheered. Everyone was happy that the execution had gone ahead.
That scene in Syria, that moment, was like a scene from the Middle Ages, the kind of thing you read about in history books. The war in Syria has reached the point where a person can be mercilessly killed in front of hundreds of people—who enjoy the spectacle.
As a human being I would never have wished to see what I saw. But as a journalist I have a camera and a responsibility. I have a responsibility to share what I saw that day. That’s why I am making this statement and that’s why I took the photographs. I will close this chapter soon and try never to remember it.
Patrick Witty is the International Picture Editor at TIME. Follow him on Twitter @patrickwitty.