when judy was murdered, larry claimed that judy was having an affair with a co-worker, james isaac, who died in a suspicious traffic accident days after judy's death. to see if it was isaac's dna on the bedding, investigators obtained a court order allowing them to exhume james isaac's body. >> when the dna profile from isaac was compared with the unidentified semen on the electric blanket, it was found to be not a match. so, the semen on the electric blanket remains unidentified. >> investigators found no evidence that judy bruce and james isaac were anything more than acquaintances. next, investigators asked dick bisbing, senior research microscopist at mccrone associates, to analyze the dirt on the bottom of larry bruce's shoes, which were still in evidence. to do this, bisbing used a polarized light microscope. >> it's like looking through polarized sunglasses. and by manipulating the light, we can see different optical properties, different optical features of each of these mineral grains. their appearance, their color, their optical properties all help us identify the type of mine