NEW YORK—For most of the last year, a white, two-story tent on a dreary side street near the East River has sheltered nearly 20,000 riddles.
The 16 refrigerated trailers inside the tent have served as the temporary resting places for 19,906 bits of flesh and bone that were recovered from the rubble of the World Trade Center.
"Every time I enter that tent, I get goose flesh," said Dr. Charles Hirsch, New York's chief medical examiner. "If I ever need to be reminded why we're doing this, that does it."
The medical examiner's office is the epicenter of the largest forensic investigation in U.S. history, involving scientists in a project never before undertaken following a mass disaster--an attempt to identify every remnant of a human life found at the scene.
So far, 1,402 victims have been identified out of 2,801 the medical examiner's office believes were killed at the trade center. Hirsch hopes to make 2,000 identifications by early 2003.
The relatively easy identification of intact bodies and big body parts is largely over. The answer to the riddle of identity is increasingly being found in the remains' DNA, the tightly wound genetic code in the nucleus of cells.
Coaxing that code to reveal its secrets is having an unanticipated result. To assign names to remains, forensic scientists are pushing forward the boundaries of DNA science at a pace they did not think possible.
"What [the medical examiner's office] is doing for the World Trade Center victims is seminal," said Victor Weedn, a leading authority on DNA identification and a research scientist at Carnegie Mellon University. "It sets a new standard for people in the field."
Because of the scale of the project, DNA is being processed faster than before, establishing new benchmarks for future DNA analyses. Also, a form of DNA inherited from one's mother is playing an increasingly important role in the project, and a fledgling technology that works with minute fragments of genetic material holds out the promise of identifying remains that have failed to yield their identity to established DNA techniques.
One of the major motivations behind this vast, $50 million effort is to provide solace to the family members who, although they have long since realized that their loved ones died on Sept. 11, have suffered the prolonged misery of not having a body to bury.
"The people at the medical examiner's office are our guardian angels," said Jennie Farrell, whose brother, James Cartier, was killed at the trade center.
Sorting out the identities of 2,801 victims would be difficult enough, but the job has been made infinitely harder because of the ways in which the office workers and rescue personnel were killed. The attack on the twin towers unleashed destructive forces upon the people inside far beyond that of other mass disasters.
To start, two fuel-laden passenger jets exploded in fireballs that almost certainly killed not only everyone on board but also scores or hundreds of trade center workers on the floors where the jets struck. Some occupants of both planes have been identified, but Hirsch said they were probably thrown out of the jets as they slammed into the towers, a split second before the explosions. No remains of the two planes' suspected hijackers have been identified, he said.
The passengers and workers around the impact zone--where fires burned at 2000 degrees or higher--have the lowest odds of ever being identified. Indeed, the ash of incinerated remains was found among the rubble.
As the fires raged and smoke billowed from the crippled towers, some occupants of the upper floors seemed to have been driven to leap to their deaths. The photographs and video of those desperate workers in the last seconds of their lives are some of the most haunting images of that day.
Falling from the 100th floor, almost the top of the trade center towers, a body would have reached a speed of 190 m.p.h. before striking the ground, according to David Taylor, assistant chairman of Northwestern University's physics department.
Victims probably remained conscious during the 8.75-second fall, according to Hirsch. No official count has been made of the number who died this way, but, unlike those killed in the towers or on the planes, their remains were more extensive and unburned, he said.