perhaps at least some of them may have had a motive to harm her. three of them we eliminated almost immediately for insufficient motive. >> reporter: but there were still two names left. one of them was a coworker. >> a woman named debra that worked with sherri rasmussen in the hospital. this person of interest was later placed by sherri rasmussen in an official capacity and problems followed almost immediately after that. >> reporter: so there was bad blood wean them? >> there was a motive. >> reporter: debra had moved to northern california. nutall asked local law enforcement to watch her and secretly try to snag a sample of her dna for comparison testing. in the meantime, nutall learned more about the second woman. he contacted john ruetten, sherri's former husband and now living in san diego. >> john involved he had been involved in a dating relationship with stephanie