Three miles north of Ground Zero, inside a lab with sterilized air and so little humidity that the simple act of breathing parches your throat, Mark Desire devotes himself to keeping a vow that turns 25 this year.
“We made a promise that we would never give up,” Desire, assistant director at the City of New York Office of Chief Medical Examiner, told The Post of himself and a team of scientists, technologists and anthropologists that has been working all this time to find, identify and return remains of 9/11 victims to their loved ones. “We promised those families that we would continue to advance the technology and never give up. That commitment is as great today as it was in 2001.
“I was here then, and am here now,” Desire said. “I feel honored to be doing this work. It’s a mission that has defined my career.”
The crew, many of whom are too young to remember the horrific attack, use cutting-edge methods to wring strands of DNA out of tiny bone fragments found at Ground Zero and match them to collected profiles. They’ve built a library of biological identifiers taken from victims’ personal items, like toothbrushes and combs, in the days days after the 9/11 attack.
Desire describes the aftermath of the attack that claimed 2,753 lives as “not only the largest forensic investigation in the United States but also the most difficult” — in part because “jet fuel, fire, water used to put out the fire, chemicals in the building and sunlight all … all destroy DNA.”
Just last month, the 1,651st victim was identified. (The person’s relatives requested anonymity and asked that the victim remain unnamed as well.) But there are nearly 7,000 fragments that Desire and his group have analyzed but not yet been able to match.
“We’ve gone back to some bones 10 times, hoping that new technology will allow us to find DNA,” explains Desire. “If it’s a very small fragment that we’ve already tried [tech] on, and it now gives us just one chance, we need to ask ourselves if we should try now or wait for the technology to get better. That’s a big decision.”
The latest tool in his arsenal: Forensic investigative genetic genealogy that allows the team to tap into genetic banks, create family trees and track down previously unknown relatives of victims.
“Let’s say we have a DNA profile that does not match anything in the [DNA] databank — possibly, that’s because no relatives came forward,” Desire said, pointing out that it could have been due to oversight during an extremely stressful period. “Sometimes, family members thought they gave a DNA sample but, in actuality, they didn’t.
“We use commercial genealogy labs to help us [get started]. Then we take the forensics in-house so the NYPD genealogist can do analysis and an investigation. All these clues help us get closer and closer to solving.”
On Sept. 11, 2001, Desire was a criminalist in the Office of the Medical Examiner, using science to identify the missing and solve crimes. When the planes hit the second building, he and his colleagues raced downtown to the World Trade Center just after 9 a.m., while both towers were still standing.
“Normally, when the fire is out and everything is safe, that’s when our team goes in. But this was all hands on deck — our job was to preserve the evidence,” he recalled. “We were to set up a temporary morgue and stay out of the way of first responders running into the buildings.”
When the South Tower came down, Desire was knocked out of his shoes and his Office of the Medical Examiner jacket was shredded. That garment and his wristwatch, which stopped ticking at the moment of impact, are framed and on display at the lab — inspiration to keep going.
On Sept. 12, he returned to work. But with fewer than 100 victim bodies fully intact, the mortuary got used largely for examining fragmented remains. “The people who could be identified, we got them back to their families for proper burials,” said Desire, who was then assigned to gathering DNA from reference samples supplied by relatives of the missing.
The process of recovery began immediately.
“We had an anthropologist tell us what were human bones, what were animal bones — from the restaurant and from people’s lunches … — and which were 300 years old, buried beneath the Towers,” Desire said.
Sometimes a victim’s belongings have been identified even when the person has not.
“A firefighter’s helmet was recovered. His name was on it and his number. We generated a DNA profile [in case other remnants are found and prove to be a match],” Desire recalled. “We returned the helmet to his family, but we have not found that person yet.”
When a person is found and their remains — even in the smallest amount — are delivered to loved ones, said Desire, “There is hugging and crying and the feeling is unbelievable. You can’t turn your back on that.”
Paul Keating can relate. In August 2025, the Floridian was notified that of positive match for his mother Barbara, who had been aboard American Airlines flight 11, which crashed into the North Tower.
“They went through the rubble centimeter by centimeter,” Keating told The Post, sounding amazed by it all. “For the first time in so many years she’s here. [The tragedy] never goes away. But any closure is good closure.”
Desire remembers the plea from a woman recalling her daughter who died in the Trade Center attack: “She said, ‘I don’t have much time, and I want to hold her once more before I die.’”
Even a tiny shard of bone would provide closure. “I said, ‘We work nonstop, every day, but I can’t predict who’s going to be next,’” Desire recalled.
“She was, like, ‘I understand. But can you promise me this: After I die, and you do find her, can you pair her with me? I want her by my side.’”
He assured the mother that she could count on his word: “We’re not going to give up.”
