The stunning image rocketed around the world, via Facebook and Twitter and other social media: an Associated Press photographer's close-up of an agitated gunman just moments after he had assassinated Russia's ambassador to Turkey.
Gun in his right hand, his left hand raised with his index finger pointed, the man is shouting angrily as his victim's body lies sprawled near his feet.
Within hours, the photo had reached more than 18 million people on Facebook; more than 430,000 people engaged with it via reactions, comments and shares. It appeared on newspaper front pages worldwide, including the New York Times, USA Today, the Financial Times, El Pais in Spain, the tabloids Liberation in France and The Sun in Britain.
The photographer, Burhan Ozbilici, was attending an exhibition at the art gallery in Turkey's capital Ankara when Ambassador Andrei Karlov was shot dead on Monday night. At first he thought it was a theatrical stunt when a man in a dark suit pulled out a gun and fatally shot the ambassador.
Like others in the room, Ozbilici was scared but despite this he came forward with his camera.
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"I'm a journalist," he later said.
"I have to do my work. I could run away without making any photos. ... But I wouldn't have a proper answer if people later ask me: 'Why didn't you take pictures?"'
Other photographs this year have gripped the world: the body of a three-year-old Syrian refugee washed ashore on a Turkish beach; another Syrian boy sitting in an ambulance in Aleppo, dazed and caked in dust, with blood covering much of his face.
AP's acting director of photography Denis Paquin said the photo shows the dangers photographers and videographers are exposed to.
Time Magazine journalist Karl Vick's said the image is instantly iconic, while Serbian writer/photographer Dunja Djudjic heaped praise on DIY Photography.
"I can't imagine how traumatic it was for those who were there at the time," she wrote.
"But thanks to a brave and extremely professional photographer, we are left with some of the most powerful and shocking documentary photos of this year."
