The New York City medical examiner says it has started sifting construction debris from the World Trade Center site in an effort to find any human remains from the 9/11 terrorist attacks.
The work began Monday. It's expected to continue for about 10 weeks.
Deputy mayor Cas Holloway said in a memo Friday that DNA testing will continue until every possible identification can be made.
City officials say about 60 truckloads of construction debris have been collected around the site over the past 2Â½ years. A skyscraper will replace the twin towers.
Some 2,750 people died at the World Trade Center in the 2001 attacks. So far, 1,634 people have been identified.