>> pelley: stacey goodman, a police detective, is one of the voices dr. ecorded in what is now called the world trade center oral history project. >> goodman: at one point, this senior... i think he was a retired fireman, he comes in. his hands are cupped. and he's got bones in his hands. and he goes up to the medical examiner and he puts the bones in front of him and he goes, "this is my son." what do you say to that? ( sniffs ) >> pelley: no one could possibly know 9/11 the way these people do. we asked several of the responders to give us a sense of the hours of testimony that they've put into dr. luft's project. >> carol paukner: the debris and the people rushing out at us, i couldn't even make it to tower one. i made it to the base of tower two. >> pelley: carol paukner was a cop, on the scene before the towers fell. >> paukner: this big, brawly fbi guy had his shield around his neck. and, you know, i looked up at him and he's telling... there was about six officers there with me, and he's like, "if you want to live, you... you might as well leave now