As of 2011, about 20,000 body parts have been found in the debris... 342 of 343 firefighters have been identified. A total of 293 "nearly whole bodies" were discovered before the barge/truck ride to Staten Island - Fresh Kills Landfill. More than 1,000 people remain unidentified of 2,753 killed there.
"Where is everyone? Why aren't we finding more bodies? Cause it's all vaporized -- turned to dust. We're breathing people in that dust."
- Brooklyn firefighter, from Christopher Ketcham, http://dir.salon.com/news/feature/2001/09/19/dust/index.html
In 2006, 74 human bone fragments were found on the roof of a neighboring building, several hundred feet below the top floors of the towers.
Robert Shaler of the New York City Medical Examiner's Office and a staff of 105 scientists worked with $13 million to undertake the largest DNA matching program ever. They "sent some of the most damaged human fragments to private forensics labs that specialize in advanced DNA-retrieval techniques. One was the Bode lab in Lorton, Va., which is known for extracting genetic material from bones. The New York team gave the lab a seemingly impossible challenge: to identify 12,000 burnt bone fragments. The bones 'had been burning in the rubble at extreme temperatures,' says Mike Cariola, the lab's director, 'and we were only getting DNA samples on half the ones we tested.' Cariola recalls that 'some pieces of bone were so charred that if you held it with two fingers it would disintegrate.'"
Video source: the Int'l Center for 9/11 Studies NIST FOIA, Release 10, WTCI-30-NYC_Pt6of6.wmv