ksm. khalid sheikh mohammed. that brings us to lawrence kobilinski. he knows his stuff. he's joining me from new york. lawrence, obviously we all remember the video. 2002. tough to watch then. absolutely no need to replay it right now. my question is this. how in the world did investigators use the image of the killer's hands to corroborate with ksm's confession he did it, he beheaded daniel pearl? >> well, brook, this is not a routine standard procedure in the arsenal of criminalists. what it is based upon is the fact that the major vessels in the hand or any other place on the body remain in the same position throughout one's lifetime barring some kind of clinical intervention. so that if you can capture an image of the position of the vanz from that video, you can then compare it to a known image. in other words, you're doing