When photographer Richard Drew arrived at the burning Twin Towers on 9/11, he was one of many journalists frenetically trying to capture some sense of the horrific chaos all around them. In the process, Drew took what may be one of the most wrenching single images to come out of that horrific disaster: The Falling Man.

Drew's photo was one of a series he snapped of a man hurtling from the top of the north tower. The man's identity remains a mystery today, though many believe he may have been an employee at Windows on the World, a restaurant atop Building 1 of the WTC.

The brief TIME video above recounts the story of Drew capturing the image—which was given its name in a widely-read piece by Esquire writer Tom Junod—as well as the backlash that followed its publication in several papers. It's a fascinating behind-the-scenes look at how a photograph that's come to symbolize the terror faced by thousands that day entered America's national consciousness.

With the 15th anniversary of 9/11 falling on Sunday, take a moment to learn this back story, and remember that man and so many others who were lost that day.

h/t TIME