The New York City medical examiner's office wants relatives of some of those presumed killed in the September 11th attack on the World Trade Center to provide more DNA samples to help identify remains found at Ground Zero.
As of Friday, 712 people of the estimated 2,843 killed in the twin towers' collapse have been matched to DNA samples submitted by relatives, the examiner's spokeswoman Ms Ellen Borakove said.
She said additional samples from victims' personal effects such as toothbrushes were needed in some cases to help identify 14,341 pieces of human remains found so far. Forensic biologists have extracted as much DNA as possible from many of the existing samples, Ms Borakove said. Some families have not submitted any samples.
In some cases, saliva swabs from a relative - especially a parent, child or sibling - can help identify remains.