As far as I know, they only identified 2 of the 10 terrorists who hit the twin towers.
http://news.bbc.co.uk/1/hi/world/americas/2808599.stm
Btw, with respect to the caller's opinion about DNA testing and it's "impossibility," you can safely discount that as standard CT willingness to insist on the "impossibility" of things in fields they know nothing about.