Ellen Niven first thought something had happened to her son when two police officers came to her door as she was decorating the family’s Christmas tree.

Instead, the officers delivered shocking news about her late husband: his remains had finally been identified, more than two decades after he vanished during the 9/11 terror attack on the World Trade Center. Until December 2023, John Niven was among the more than 1,000 victims of the attack without identified remains. 

The New York City Office of Chief Medical Examiner continues to fulfill its promise to identify 9/11 remains for as long as there are families looking for answers.

“I thought that that door had long been closed,” Ellen Niven said. 

The search for remains at ground zero

After the attack, families with missing loved ones lined up at a National Guard armory and waited hours to give DNA samples to the medical examiner. 

The medical examiner’s office collected 17,000 reference samples, including toothbrushes, razors and hair brushes — anything the person touched while they were alive, according to Mark Desire, assistant director of forensic biology.

Niven’s 18-month-old son had his cheek swabbed for DNA. His father, who’d been in the South Tower during the attack, was among those entombed in nearly two million tons of debris. 

After a year of combing through debris, first responders thought they had found everything. But then in 2006, bone fragments were found on the roof of the Deutsche Bank building across from ground zero. The medical examiner sent anthropologist Bradley Adams.

 “We ended up going through the whole rooftop and we found over 700 small bone fragments on that rooftop. And then we ended up, you know, obviously if there’s remains there, we need to search other areas,” Adams said. “So, we went through every floor of that building, even to the point of having vacuum cleaners and vacuuming up dust and debris.”

Five years after the attack, Adams began collecting 18,000 tons of excavation material. Dozens of anthropologists washed it through screens. In addition to the 700 bone fragments found at the Deutsche Bank, over a thousand more were found during additional sifting operations at ground zero.

The challenge of identifying the remains

Today, 40% of the 2,753 victims of the World Trade Center attack remain unidentified, according to Dr. Jason Graham, New York City’s chief medical examiner. 

“As long as there are families who are continuing to seek answers, this work will continue,” Graham said. 

Desire, the assistant director of forensic biology, works to put names to the remains. 

“These remains went through every possible thing that could destroy DNA, from jet fuel to diesel fuel, mold, bacteria, sunlight, all kinds of chemicals that were in the building,” Desire said. “Everything was present at ground zero, making this not only the largest forensic investigation in the history of the United States, but the most difficult.”

Some remains have been tested 15 times without a result.

“But if there’s DNA, we’re going to find it,” Desire said. “We’re going to generate a profile. It may take us a while.”

All remains today are bone. In a demonstration with animal bone, Desire explained new technologies that make breakthroughs possible. They include a cryogenic grinder, filled with liquid nitrogen at 320 degrees below zero. 

With high speed vibration, individual cells in the deeply frozen bone shatter —a chemical process that releases their DNA. Other innovations chemically amplify DNA, revealing more information from the smallest fragment. 

“Some as small as the size of a Tic Tac, we’ve been able to get DNA from those and generate a DNA profile,” Desire said.

Samples are tested every week with advanced technology.

Identifying John Niven’s remains

John Niven’s bone fragments, 15 in all, had been tested for years. 

“I heard nothing about John’s remains for 22 years. So, we just assumed that there was nothing. We buried a box of mementos –photographs and a letter that I wrote, and a drawing my son had done,” Ellen Niven said.

She remarried and had two more boys. Her son Jack was 18-months-old when his father died. Last year, the medical examiner’s lab made a perfect match to the cheek swab taken from Jack when he was a baby. 

“The police came to the door and my first reaction was, I said, ‘Is it my son?’ And they said, ‘No, everything’s OK,'” Ellen Niven said. “And these two wonderful, really kind policemen said, ‘We’re here to deliver you the news,’ and they had a letter, ‘That your husband’s DNA has been discovered.'”

Jack and Ellen Niven took the news differently.  

“For me, it was very sad. For him, it was uplifting, in a way, to realize that people had been working all that time to find any piece of his dad,” Ellen Niven said. 

World Trade Center remains identified 

Every remain identified from the World Trade Center has a unique identification number. Number 18,756 is Andrea Haberman’s most recently identified remain. The 25-year-old woman was visiting New York for work on 9/11 and was in the North Tower when it was hit.

Her parents, Kathy and Gordy, her sister Julie, and her fiancé, Al, drove 16 hours to Manhattan after the attack. They visited 32 different medical centers searching for Haberman, but they were unable to find her. 

The Habermans would like to be told of all new identifications. 

“If Andrea could face what she had to face, how could I not want to know what happened to her?,” Gordon Haberman said. 

Today, he’s 73. His relationship with the medical examiner has spanned 11 notifications, plus the amazing discovery of the contents in Andrea’s purse. He received them in 2004 during a meeting with police officers and a priest. 

“They wanted to know if I needed any help processing that,” he said. “And I was actually more concerned at that time [with] how I’m going to keep these from my wife.”

He feared his wife’s pain, so he locked the bag in a desk drawer, which he did not open for seven years. In 2011, they donated the contents of the purse to the National September 11 Memorial & Museum at ground zero. 

There’s Andrea’s phone –which her family kept calling that day– a pager, a driver’s license and her visitor ID, the last photo taken of Andrea.

“That was our Andrea,” her father said. “And she was going to go on to do great things and she wanted grandchildren, and her house was such a pride and she loved her Al so much.”

He brought Andrea’s identified remains home to Wisconsin, but he believes her other remains, still unidentified, are in the museum, which houses the medical examiner’s repository for 9/11 remains.

“I don’t consider it a burden”

Families have a choice when an identification is made, according to Dr. Jennifer Odien, the medical examiner’s World Trade Center anthropologist. They can ask a funeral home to pick up a remain, vacuum packed and labeled with an American flag. Or they can leave it in the custody of the medical examiner. 

“I tell them that they don’t have to make that decision right now. They can call back in a month, a year, two years, 10 years. And we could then have those remains transferred over to the funeral home that they choose,” Odien said. 

While the Habermans have asked to be notified every time there’s an identification in their daughter’s case, many families don’t want to know. About half of 9/11 families have told the medical examiner that if their loved one is identified today, they don’t want to know. 

Few understand the emotion in the choice like Odien, who acts as something of a counselor to those families. She’s in touch with hundreds of families and listening is a vital part of her job.

“I will listen as long as they would like me to. We have phone calls sometimes and it’ll last an hour,” she said. “And I will stay on and listen and talk to them. When they have a question, I’ll answer it. But a lot of times they just want to speak to someone.”

Odien also meets with families at the National September 11 Memorial & Museum at ground zero. Inside, there’s a reflection room, open only to families of 9/11 victims. Families can call a number on the door to summon an escort. Odien will often sit or walk with the families during emotional visits.

“I don’t consider it a burden. It’s tough. I definitely have moments of, you know, feeling very emotional and needing to step back,” she said. “But when I talk to a family and they say thank you, how grateful they are with our continued work, that a question I’ve answered helped them in some way, it makes it all worth it.”