9/11: DNA breakthrough helps identify more victims of deadly terrorist attack 17 years later

About a thousand victims are yet to be positively identified

Advancement in DNA testing has led to the identification of more victims of 9/11, 17 years after the deadly terrorist attack in New York City rocked the world.

The death toll after two planes hijacked by al-Qaeda extremists were flown into the twin towers of the World Trade Centre was 2,753, but around 1000 of the victims are yet to be positively identified.

Ahead of the 17th anniversary of the atrocity, a team of experts announced a scientific breakthrough in the extraction of genetic material from Ground Zero.

The new technique works by placing bone fragments in a chamber containing liquid nitrogen to make them more fragile so they can be pulverised into fine powder. The more a bone is broken down, the more likely scientists are to make a successful DNA extraction.

"We're going back to the same remains that we've tried five, 10, 15 times," Mark Desire, who leads the Medical Examiner's crime lab said.

"We are making DNA profiles from remains we had no hopes of identifying in the past," he added.

The pioneering method made it possible to identify financial worker Scott Michael Johnson, 26, who worked on the 89th floor of the south tower.

While many may welcome the latest findings from the largest forensic investigation in US history, the update has opened old wounds for families of those whose remains may have been buried in a landfill site.

Fresh Kills Landfill - a waste site on Staten Island was covered with layers of soil and other materials to prevent the release of toxic gas from decomposing rubbish into the atmosphere.

Diane Horning, who led a failed court battle by a group called World Trade Centre Families for Proper Burial, to stop the city from building the park in the wake of the tragedy, said the advancement offered little consolation to grieving families.

"We are grateful that the identification continues, but there is more material that could have been part of that had the city not been so cavalier with us," Ms Horning said. Her 26-year-old son Matthew was one of those identified early on.

Charles Wolf, whose late wife Katherine has yet to be identified insists that if they are in the sealed landfill, he considers it "God's will" and he is "at peace" with it.

"What’s the remedy? Dig everything up and risk exposing all those toxins again to the environment?” Mr Wolf said.

"No, that’s not the answer, because all of a sudden now the cure is worse than the disease.”

Addition reporting from Reuters.