but one of their scientific experts had a suggestion. >> i said we need to get a sample that was more intimate from him. we need to get a sample which he had touched or used, such as a cigarette butt or a toothbrush, or an item of clothing. >> but that wouldn't be easy. it seemed planten knew he was being followed. >> surveillance was conducted on drew planten for a week, at work and at home, and we could not obtain any dna from that week's worth of surveillance. >> ultimately, investigators followed planten to a restaurant. but planten was one step ahead of them. >> he ate nothing but finger foods. when he would get up to go to the bathroom, he would take his straw out of his cup and put it in his pocket and take it to the bathroom with him. he flushed all of his napkins.