I meet with these people and I feel their angst and their pain and the people in our laboratory feel the same way

Dr Robert Shaler

Speaking near the ruins, three months to the day after the attacks, he said that his team hoped to get full DNA profiles from up to 50% of samples while the remaining 25% would yield only partial results.

"We don't believe we have samples for everyone who died," Dr Shaler told BBC News Online.

He spoke of the difficulty of piecing together profiles while being aware all the time of the anxiety of the loved ones of those missing.

"I meet with these people and I feel their angst and their pain and the people in our laboratory feel the same way," he said.

Nothing overlooked

Five laboratories were working on the identification of the victims across the United States and a "long process" still lay ahead, Dr Shaler said.

But he believed that the labs had collected "virtually all of the family samples" they needed.

We're testing every single thing that comes into the lab

Dr Robert Shaler

In their work to match them up, the forensic scientists are examining almost 11,000 samples from the WTC site, including "clothing and bones or whatever it happens to be".

Most of the bodies form the site are "not intact", the forensic director said.

99th floor

"We're testing every single thing that comes into the lab," Dr Shaler said.

He pointed out that new, virtually untested techniques were being used on samples which yielded partial DNA results.

"We are making identifications every day," he said.

Dr Shaler also played down the theory that those killed in the actual explosions from the impact of the two airliners were unlikely to be identified.

He quoted a survey that showed that all of the victims identified by DNA had been located above the 99th floor of the WTC One building.