The identification of victims from the Sept. 11 attacks on the World Trade Center may soon get a boost thanks to a scientific advancement borrowed from the U.S. military, officials said Thursday.
While remains from more than 1,600 victims of the attacks have been identified by the New York City Office of the Chief Medical Examiner, the pace of that process had stalled because of limitations on DNA technology. An average of about one victim a year has been identified in the past three years, officials said, and more than 1,100 victims still cannot be genetically matched to remains recovered from the Twin Towers.
But DNA advances used by the military now mean identifications can be made from degraded genetic material once deemed unusable, officials said Thursday during a media tour of the lab where technicians have been identifying World Trade Center remains for the past 17 years.
Known as “next generation sequencing,” or NGS, the technique was first perfected in 2016 by U.S. Department of Defense officials in collaboration with scientists in Europe and the United States. It is being used to identify 866 unknown American soldiers whose remains were repatriated after hostilities ended in Korea in 1953. The remains had been embalmed — which unknowingly altered the DNA — and were buried in the National Memorial Cemetery of the Pacific in Hawaii.
“They have made a lot of great progress,” Tim D. Kupferschmid, chief of laboratories for the OCME said Thursday of the military effort, adding that his lab received recent grant money for further studies of NGS with the idea of using the method in New York.
“It looks very hopeful," Mark Desire, assistant director of the city medical examiner’s office department of forensic biology, said earlier. “We are evaluating that technology right now. That will allow us to look at samples that are even further degraded, with even smaller amounts of DNA.”
NGS is the second scientific method borrowed from the military's identification of American war dead in the effort to identify Sept. 11 victims. Because some war remains were chemically or bacterially damaged, defense department officials in 2006 came up with a method of “demineralization” in which the bones' fragments are reduced to powder and chemically treated to release DNA fragments for analysis, said Timothy McMahon, director of the DOD DNA Operations in Dover, Delaware.
On Thursday, Desire and other OCME officials demonstrated the demineralization process, using a special device to pulverize a bone segment into a fine powder. Previously the bones were pulverized by hand, using the classic mortar and pestle. The results of demineralization testing helped officials make the most recent identification from the World Trade Center in July: Scott Michael Johnson, a 26-year-old securities analyst who worked in the south tower.
Carl Gajewski, 48, of Manhattan, a supervisor in the DNA lab who worked on the Johnson identification along with the other criminalists, said, “I was the first one to see the search come back. I knew immediately it was an identification. It was a sense of fulfillment.”
“We really don’t lose sight that these are remains of humans,” Gajewski emphasized.
Immediately after the 9/11 terror attacks, officials were able to more easily identify victims from the World Trade Center because the remains still contained useful DNA. Dental records, fingerprints and personal effects were also used.
But as time went on, the DNA degraded. In some cases the intense fire from the jet fuel destroyed the DNA in bone fragments, which some experts said will never yield results no matter how far technology advances, officials said.
Another problem, said former city medical examiner Michael Baden, was the decision to quickly excavate the World Trade Center site and transport the debris to Staten Island by truck and ferry for sorting on a conveyor belt at a landfill. That process, said Baden, mingled remains and in some case may have destroyed or lost them.
Desire said OCME personnel were present during the excavation to look at any remains found and the late Dr. Charles Hirsch, the city medical examiner during 9/11, decided to dry out any remains recovered to help preserve DNA.
NGS has generated useful genetic results from nearly 50 percent of bone fragments from the Hawaii monument and several other wars — fragments the military once considered too degraded or too chemically altered, said McMahon.
Essentially, NGS extracts usable mitochondrial DNA from bone samples. Mitochondrial DNA is a type of DNA found in all human cells but is only transmitted through the maternal line. The other type of DNA, often used in criminal cases, is nuclear DNA, sometimes referred to as autosomal DNA, which comes from both parents. When autosomal DNA is degraded or chemically altered, such as with the World Trade Center cases, NGS can help find mitochondrial DNA to compare with a reference sample from a victim’s mother, brother or sisters.
McMahon likened the NGS process to the use of a stick with bubble gum at one end to recover a silver dollar from a sewer grate. In McMahon’s simplified explanation, the coin extracted from the sewer represents a usable piece of mitochondrial DNA pulled from surrounding bacteria.