Matching DNA Samples
Once cells are damaged, the DNA contained within them begins to disintegrate. The more heavily damaged samples with degraded chromosomal DNA will be analyzed by Celera, which can create a genetic profile based on another kind of DNA (mitochondrial) also found in the cells.
Meanwhile, relatives are proving medical examiner's office with personal items that may contain DNA samples of the possible victims. The New York City medical examiner's office will analyze these DNA samples to compile a "genetic fingerprint" that can be compared with the tissue from the site.
Relatives and friends have been pouring into a Family Assistance Center in Manhattan to deliver a variety of items that were used exclusively by the missing persons: combs, brushes, toothbrushes, razors, undergarments, eating utensils, cigarette butts, and chewing gum.
Some estimates have suggested that rescue workers won't finish combing through the debris until at least early next year. It's not known how long the tissue could be useful for genetic testing, although cold weather would help preserve the tissue and its DNA.
In a statement, New York City Mayor Rudy Giuliani said: "DNA evidence offers us the best opportunity to help families find their loved ones. I strongly urge everyone who is missing a relative to participate in this process."