N.Y. medical examiner continues DNA probe

Thousands of questions remain in aftermath of Manhattan tragedy

October 27, 2002|By Robert Lee Hotz | Robert Lee Hotz,SPECIAL TO THE SUN

NEW YORK - The human remains of the day shelter in the shade of a white tent near the East River's edge.

Here, set off by wilted bouquets, are the unanswered questions of the World Trade Center dead, stored in the 16 refrigerated trailer trucks parked on this shaded sliver of vacant pavement.

Each question is an anonymous flake of human bone or fleck of flesh picked from the rubble and preserved in a scientific limbo. There are 14,994 of them. This is death divorced from identity - body parts without names to claim them; names without remains that can be mourned.

These human fragments are the dark heart of an unconventional murder mystery that will take years to solve. There is no question who committed the Sept. 11 attack or why terrorists may have acted as they did; little question now of the 2,797 names of those who died. The only answer authorities still seek - at a cost of $58 million since last fall - is how to settle those names on these unidentified remains. Only half the dead have been identified so far.

The search has brought investigators to the edge of what science can discern of death.

By necessity, forensic specialists led by Dr. Robert Shaler, head of forensic biology at the New York Chief Medical Examiner's Office, are virtually reinventing the science of identification.

Their pursuit of identity has turned the busiest morgue in the United States into a laboratory at the forefront of human gene research. They are forging the new tools of 21st century forensic medicine.

They are creating better ways of handling DNA, perfecting new genetic testing techniques, and developing computer programs to analyze genetic variations. The new techniques one day may help diagnose inherited traits across the entire human population.

`New territory'

"We are moving into new territory," Shaler, 59, said. "I feel as nervous as I did the first day of the attack."

In its scale and scientific demands, the federally financed World Trade Center investigation is unique in the annals of crime and forensic medicine, experts said.

In an effort that rivals the Human Genome Project, Shaler has marshaled a national network that includes the New York State Police, the FBI, six biotechnology companies, a score of DNA consultants, computer software developers and an advisory committee of 30 forensic experts that has met every eight weeks to thrash out technical issues.

So crushed, burned, waterlogged and corroded are these remains that they defy conventional identification techniques, forensic specialists quickly discovered.

Consequently, almost half of the identifications made so far have been solely on the basis of genetic testing - 682 of the 1,411 named - and DNA analysis helped in the identification of 343.

Of the unidentified remains, there is not enough undamaged DNA to build a normal genetic profile.

Even now, no one can even tell how many people these refrigerated tissues encompass. No one knows how many people vaporized in the fiery crashes and collapsing towers.

The fires took three months to extinguish. Crews sifted 1.6 million tons of debris for nine months to exhume the remains.

Death crushed some people so fiercely that only genetic analysis has been able to tell their intermingled cells apart.

The forensic experts so far have matched 4,930 body pieces to 1,411 of the victims, and given over many of them for burial or cremation.

"If this had occurred in 1980, or even 1990, the forensic work would have to stop now, with only half the people identified after heroic, intensive work," said noted forensic anthropologist Clyde Snow, who helped pioneer modern identification techniques.

600 more identities

By pushing the state of the forensic art, Shaler is hoping to identify remains of at least 600 more victims.

In recent weeks, the forensic experts have invented more refined testing techniques to extract usable DNA. They are retesting every one of the thousands of unclaimed pieces of bone, flesh, hair and clotted blood samples.

Conventional genetic testing - the mainstay of the effort so far - is reaching its limits. Shaler is resorting to experimental genetic techniques never before used on such a scale.

Since June, DNA experts at Celera Genomics in Rockville, Md., have processed 19,000 DNA specimens from victims and relatives, examining the genetic material contained in the thousands of mitochondria in every cell. The DNA in these cellular power plants is inherited directly from each person's mother. It is much smaller than DNA found in the nucleus of a cell, but is much tougher and more likely to survive intact in damaged tissue.

This month, forensic experts at Orchid Cellmark Inc. in Germantown, Md., expect to begin tests that look for single variations in the 3 billion characters of the human genome. These differences - called single nucleotide polymorphisms - are part of the reason every individual is unique. So far, scientists have mapped 1.4 million of these molecular variations in humankind.

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