The last image of firefighter Gary Box on September 11, 2001.
Gary, then 35, had been working as a firefighter in Brooklyn for roughly five years when the terrorists attacked. He did not speak to his father the day of the attack and his body was never recovered, leaving the circumstances of his death a mystery.
On September 11, 2009, Gary's sister, Christine, was visiting the Tribute Center when an employee asked her if she was looking for someone specifically.
She mentioned her brother Gary, and the employee showed her to a picture of a firefighter in the Brooklyn Battery Tunnel that had a caption bearing Gary's name.
But it was not Gary. It was a photo of Brian Bilcher, another member of Gary's fire squad who also perished on 9/11.
The discovery compelled Gary's father to dig deeper, clinging to the possibility that there could be a similar picture of his son out there.
His father scoured photo archives of the National 9/11 Museum and the memorial's website, which allows users to upload photos from 9/11 directly to the site.
After searching one night for more than five hours, he went to sleep, physically and emotionally exhausted.
The next morning, his wife, Helen, called him into the living room as he was eating breakfast.
She showed him a photo of a firefighter running through the Brooklyn Battery Tunnel toward the Towers alongside cars stuck in traffic.
This time, it was Gary.