>> there were more than a dozen cigarette butts. police hoped at least one was from daniel woloson. they gave the evidence to dna analyst jennifer andrew. >> what i gathered from speaking to the investigator in charge, there was a homicide about 20 years ago of a college student, and you know, me being recently out of college, it was a little bit personal for me. >> one by one, andrew cut open the cigarette filters often a good source of dna. >> because that's where all the saliva and skin cells would be deposited. >> the samples were treated with a solvent that separates the dna. a profile was generated from an unknown male. the profile was sent to illinois for comparison with the 20-year-old genetic material left at susan schumake's murder. and it matched daniel woloson. naturally, lieutenant echols