so krastek turned to dr.g dna data. andrea canning: had it been used before in court? or was this the first time? - never. this was the first time. andrea canning (voiceover): at the time of the trial, fbi dna analysis was still being done by agents, not a supercomputer. it's like comparing a ferrari with a go kart. andrea canning (voiceover): perlin's computer analysis in the foley case had come up with an astonishing result. the prosecutor thought it was the smoking gun. according to perlin, this was definitely foley's dna, 189 billion to 1. andrea canning: 189 billion to 1. what exactly does that mean? in this case, what it means is that a match between dr. yelenic's fingernails and defendant kevin foley is 189 billion times more probable than a coincidence. andrea canning (voiceover): to defense attorneys richard galloway and jeffrey manzo, the dna evidence was more a smokescreen than a smoking gun. andrea canning: you tried to discredit the science, the dna. what was your strategy with that? richard gall