The pieces of bones are small.
They range in size from a couple of inches to tiny specks that could fit on a fingernail. But they are the latest and biggest hope for families of the more than 1,100 people killed on Sept. 11, 2001, at the World Trade Center whose bodies were never found.
In recent weeks, officials said a group of forensic anthropologists working with New York City's Office of the Chief Medical Examiner have identified 48 new pieces of bone found in newly discovered debris from the trade center as being human remains. Forensic scientists are trying to match the new findings to a huge DNA bank in hopes of making some identifications.
The latest bones were found in 844 cubic yards of debris collected from previously inaccessible areas such as catch basins and tiny spaces between buildings at Ground Zero near West and Cedar streets, as well as the roadway going into the site. The material was trucked to the Fresh Kills site, where earlier sifting operations have taken place.
Began in April
New sifting began in April and will continue through June. Last Wednesday another fragment that is potentially human was uncovered, officials said.
The fragments are taken by van to the medical examiner's office in Manhattan on East 30th Street. There, the bones undergo DNA testing to see if they can be matched to any of the victims: those whose remains were never found or those who have been discovered previously. Since 2001, DNA alone has identified 879 victims of the 2,752 who died when terrorists flew two airplanes into the Twin Towers.
The finds are the latest in DNA recovery efforts that have cost at least $50 million in mostly federal funds since 2001, said Ellen Borakove, a spokeswoman for Dr. Charles Hirsch, the city's medical examiner, whose office sends out daily e-mail reports on the sifting efforts.
None of the forensics experts working under a tent housing a conveyor belt and fine screens at the Fresh Kills site was available for interviews.
But other forensic anthropologists said sometimes it only takes a glance at a bone to determine if it is human.
Often easy to tell
Where necessary, microscopic examination of the fragments is used.
DNA analysis is complex and is expected to take at least a few months, said Borakove.
But a major stumbling block is that DNA degrades over time, especially when exposed to the elements, said Dr. Robert Shaler, who ran the city DNA lab until retiring in 2005.
"My guess is the DNA in those bones is pretty much beyond recovery," said Shaler, now a professor at Penn State University. "It is possible they might find something. . . . I hope they do."
Since 2006, newly discovered Trade Center remains have led to 25 victim identifications and the discovery of 27 new DNA profiles that weren't in the existing database, records show. The latter could be from illegal immigrants whose families haven't come forward with reference samples, city officials said.
Borakove said the agency is asking for families of the missing who haven't donated samples to do.
She said Hirsch committed his office to continue working as long as necessary on the DNA project, despite criticism from some family members that the city has mishandled the identification process.
"He has made a promise to the families that we will try to make identifications as long as there is new technology available for us to use," Borakove said.