desperate for answers, detectives called in forensic investigator eric berg. they wanted another opinion on whether or not something could be done with those sheets because they had reached the limit of what they were able to do with chemistry. >> berg took a digital photograph of the print on the bed sheet and scanned it into his computer. the problem was immediately apparent. the ridge details on the print were obscured by the thread patterns on the sheet. as if a screen had been placed over the print. >> well, i want to find out who left this because i think it's my bad guy. i see the outline of a hand but i can't see the details. hugh do i get rid of that screen? that's really the question i'm asking myself when i'm looking at the screen. how do i get rid of that? >> then berg had an idea. he needed some way to remove the thread pattern from the image, but he needed to find some kind of filter. >> the filter is a nice word for algorithm. it's a mathematical process that can go through an image and do something to it. we have one that i designed that basica

eric: secretary of state john kerry is defending the controversial prisoner swap for army sergeant bowe berg, dismissing claims that freeing those five top level terrorists will put lives of u.s. soldiers overseas in danger. house intelligence committee chairman mike rogers and others don't buy that. >> this was the wrong message at the wrong time and we'll pay for this decision for years. this should not be about did congress get invited to the party this is about honest discussion about ramifications. >> you're very clear -- eric: kt mcfarland, former assistant secretary of defense for the reagan administration and fox news national security analyst joins us this morning. kt, ba -- loan any, huh? >> baloney, of course the united states military are not at risk. we're not leaving bases. we're ending combat role. we'll be there in two more years as training role. what does that mean. they don't go out of their bases. those bases are pretty secure places. you know who is at risk now? the aid workers, americans gone over to be school teachers to teach afghan girls how to read. american doctors