karen oswald : it did develop. andrea canning : so the palm print turned blue? karen oswald : yes.canning : and thats a big deal? karen oswald : its tremendous deal. andrea canning : while oswald and her team examined the prints, other investigators tested the blood to see who it belonged to. karen oswald : the blood came back to sarah goode. andrea canning : oswald believed the killer had attacked sarah, got her blood on his hands and then carelessly left his prints. so thats why detectives had been gathering handprints from every potential suspect. the prosecutor says they knew if they could find a match, they could likely solve this crime. andrea canning : its almost like it was the killers calling card. janet albertson : it was his signature. andrea canning : the print specialist was able to compare that bloody signature with those of potential suspects detectives sent her way. karen oswald : you dont always know homicides level of interest in somebody. youre going to compare these prints to anybody they ask. andrea canning : and one by one she checked for possible matches help