How new DNA techniques can help identify 9/11 attack victims?

Through innovative technology, the coroner's office said it was able to identify recently the remains of financial agent Scott Michael Johnson, 26, who worked on the 89th floor of the South Tower.

New DNA testing techniques are helping to identify more victims of the September 11 attacks at the World Trade Center, scientists at the New York City coroner's office said on Thursday.

It remains to identify the remains of more than 1,000 of the 2,753 dead left by the attack of two planes hijacked against the Twin Towers.

Through innovative technology, the coroner's office said it was able to identify recently the remains of financial agent Scott Michael Johnson, 26, who worked on the 89th floor of the South Tower.

In each of the last five years, a victim has been identified thanks to discoveries made since 2001. Researchers at the world's largest crime lab achieved such advances by re-examining bone fragments they had previously studied without success.

"These are all samples that we had examined in the past," said Mark Desire, who heads the coroner's crime lab. Together with her team, Desire showed the steps of the latest DNA analysis technique, which is used in fragments of human bones recovered from the attack.

The latest DNA analysis technique, known as the "World Trade Center Protocol," has been used to help identify victims of railroad and aircraft accidents and terrorist attacks in Argentina, Canada, South Africa, and other countries, Desire said.

The scientists showed how they clean the bone, pulverize it into powder, add chemicals, incubate the sample and then place it on a large automatic white machine that extracts all the recoverable DNA from the damaged material.

The more a bone is pulverized, the more likely it is to extract DNA. The new step is to place the bone in a chamber that contains liquid nitrogen - which makes the bone more fragile - shake it until it turns to dust.

Desire praised the chief medical examiner who decided in 2001 to preserve human remains in anticipation of the advances that could occur in DNA identification technology, which makes it possible for scientists to identify the victims years later.

"If we had not taken that measure in 2001, those remains would have continued to deteriorate and break down, and the DNA identifications we're doing this year would probably not be possible," Desire said.