NEW YORK, Feb. 23 -- They are the unknown lost, the 1,161 victims of the World Trade Center attacks whose bodies could remain forever unidentified.
The city medical examiner's office said Wednesday that it is halting the painstaking job of trying to identify more remains of those who died in the 2001 attacks on the twin towers in Lower Manhattan. Forty-two percent of the 2,749 victims remain unidentified.
For more than three years, forensic experts labored over bone and tissue fragments, trying to extract strands of DNA to divine the identities of lost fathers, mothers, brothers, sisters and friends.
"This is a pause -- we've exhausted the limits of the technology as it exists today," said Ellen Borakove, the New York medical examiner's spokeswoman. "But the doctors have promised -- promised -- that we will never say 'case closed.' "
Staffers at the medical examiner's office had been notifying families for three weeks when the news broke this week of the pause. Few of the families expressed much surprise, and fewer still faulted the efforts of the doctors and technicians who worked so long.
Sally Regenhard lost her son, Christian, in the collapse of the towers. He was a strapping 28-year-old firefighter with a love of painting and books, and he was at his stationhouse in Red Hook, Brooklyn, when the emergency call came on Sept. 11. Regenhard has no idea which tower her son ran into.
"Oh, God, it puts an end to hope that we might get some sort of answer," Regenhard said. "For me, the chance to find out what exactly happened to my son is over. For so many families of firefighters, our sons and husbands have disappeared into death."
Monica Iken's husband, Michael, was a bond broker, working on the 84th floor of the South Tower. No part of her husband has been found.
"The emptiness of not taking someone home is beyond being able to explain," said Iken, 34, a schoolteacher by training who now leads September's Mission, an organization dedicated to creating a memorial. "But you also get to a point where what are you going to get back? A fragment of a person? Is that my husband?"
In the days after the attacks, hundreds of forensic pathologists, anthropologists, dentists and doctors -- many of them volunteers -- flocked to three huge tents outside the East Side Manhattan headquarters of the medical examiner's office. There they pored over body parts large and small, taking fingerprints and tooth prints and X-rays, and where possible seeking a match with a list of those missing. They made hundreds of relatively quick identifications in those first weeks and months.
Then began a more laborious process. The office collected hair and saliva samples from thousands of families, and set about trying to extract DNA from almost 20,000 body parts collected from more than 2 million tons of debris. This involved standard DNA analysis, which attempts to read sequences of DNA that are several letters long. But it also forced scientists to explore new forensic techniques, in which they attempted to extract much smaller fragments of degraded DNA.
This went on for years before the forensic scientists realized that they had butted up against the outer wall of existing technology.
"I'm still driven by the families," Robert Shaler, director of forensic biology at the medical examiner's office, told reporters in 2003. "When I see these people, they look at me with eyes that say, 'Did you find her yet?' But when you're only turning out a couple a week. . . . It's hard."
The city has 9,720 unidentified body parts, which biologists have freeze-dried and carefully stored, in hopes that someday new technology will allow for a reexamination.
Regenhard had a memorial service at St. Patrick's Cathedral for her son on Oct. 26, 2001 -- she knew long ago that she would never retrieve his body. "One of these days, one day, I'll have a proper burial in a cemetery," Regenhard said. "I'll put in his mountain-climbing gear, his Spanish-language books, his artwork."
"It seems so strange." She inhaled deeply and paused. "Don't I have to do this? Don't I have to put up a tombstone and let someone know that this great kid lived his life?"