ernie scherer is charged with murdering his parents. the evidence against him was largely circumstantial except for a small slip of paper discovered at the crime scene that could be the key to blowing the case wide open. here again, keith morrison. >> it was september 2010, just months before ernie scherer iii was to go on trial for the murder of his parents. prosecutors pored over the evidence scott dudek and his detectives had collected. was there anything else? anything they missed, they might use to seal the case against ernie scherer? and that's when they saw it. something quite odd. >> they came across a piece of paper that we had collected that had blood droplets on it. >> just one small piece of paper, which one of the