mr. deparvine is involved in the murder. erefore, we don't have enough information to draw a search warrant. >> without a warrant, police couldn't get a genetic sample directly from deparvine. but there were other ways. >> we were looking for him to either eat something, drink something and discard it, chew gum and discard it, or even spit so that we could swab that up. >> a team of detectives was assigned to follow deparvine everywhere he went, hoping to somehow get his dna sample. deparvine had earned a law degree while he was in prison, and he was very careful, either because he was disciplined or he knew he was being followed. >> he led a very monotonous, very bland type of life. >>> would get up in the morning. he would go to work. he would come back home and stay inside his little apartment and go to sleep. >> deparvine was a construction worker, and he had no social life to speak of. for months, the surveillance continued with no luck. but deparvine made a mistake during the christmas shopping season. he stopped at an

mr. deparvine. >> deparvine discarded the cup and the spoon, and investigators immediately retrieved the spoon from the trash. >> the technology has become incredibly sensitive and incredibly powerful. and there is the ability to obtain dna from the smallest piece of evidence in a very reproducible, very reliable manner. >> on the spoon, scientists found saliva. they extracted dna and compared to it the blood found on the steering wheel of the van dusens' jeep. the results left no doubt. >> the dna profile that was developed from the steering wheel was matched to the dna profile that was obtained for william deparvine, his known standard. >> william deparvine? >> william deparvine was arrested and charged with first-degree murder.