NEW YORK The New York City medical examiner's office says more possible pieces of human remains have been found during the sifting of newly uncovered debris from the site of the September 2001 terrorist attacks.
The office says 21 potential human remains were recovered Wednesday. That brings the total found during the current effort to 39.
About 60 truckloads of debris that could contain tiny human bone fragments have been unearthed by construction crews working on the new World Trade Center tower in recent years. City officials say investigators will spend 10 weeks trying to find remains in that debris. The city's last such effort ended in 2010.
Some 2,750 people died at the World Trade Center in the Sept. 11 attacks, but remains of only 1,634 people have been identified.
The city's last sifting effort ended in 2010. This time, crews were able to dig up parts of the trade center site that were previously inaccessible to workers, the city said.
Since 2006, the remains of 34 previously unrecovered victims were identified through DNA, CBS New York reported.
About 9,000 human remains recovered from the ruins of the World Trade Center remain unidentified because they are too degraded to match victims by DNA identification. The remains are stored at an undisclosed location monitored by the medical examiner's office and will eventually be transferred to a subterranean chamber at the National September 11 Memorial & Museum.
Some victims' families expressed impatience that the city has only just uncovered more debris.
"Quite frankly, they should've excavated this and searched it 12 years ago," said Diane Horning, whose son, Matthew, died in the attacks. "Instead, they built service roads and construction roads and were more worried about the building and the tourism than they were about the human remains."
The city's efforts to identify Sept. 11 victims have long been fraught with controversy.
In April 2005, the city's chief medical examiner, Charles Hirsch, told families his office would be suspending identification efforts because it had exhausted the limits of DNA technology.
But just a year later, the discovery of human remains on a bank tower roof and then in a manhole near ground zero outraged families who said the search for their loved ones had been rushed initially. The findings prompted a renewed search that cost the city tens of millions of dollars and uncovered 1,500 pieces of remains.
Meanwhile, some victims' relatives sued the city over its decision to move 1.6 million tons of materials from the trade center site to the Fresh Kills landfill, saying the material might contain victims' ashes and should have been given a proper burial.
The lawsuit was dismissed, and unsuccessfully appealed to the U.S. Supreme Court.
As it embarks on combing through debris yet again, the medical examiner's office says it will keep monitoring the site as long as new areas are being dug or exposed.
Charles G. Wolf was pleased to hear about the renewed search, though he believes that his wife, Katherine, was vaporized during the attack. Investigators have never found her remains.
Years ago, it bothered him that he had no grave to visit. Wolf said the opening of the Sept. 11 memorial has filled a hole in his heart, but he'll never have closure.
"You heal. You carry on," he said. "It's not closure."