investigators hatched a plan. rachel would invite sheila to her house. as hidden cameras rolled, she would try to get sheila to incriminate herself. >> we were close by in case something happened. >> sheila did come over. police didn't record anything to pin sheila to the crime. >> the girls did not disclose anything specific. they were just very casual. >> a few days later, the police went to sheila's house with a warrant. >> we seized every kitchen knife we could find. the fbi had seized sheila's car and they were able to find presence of dna in the trunk. >> dna in sheila's trunk. if it proved to be skylar's, it would be critical to gaskins' case. a direct link. connecting the girls to skylar's death. they shipped the sample off to the lab and waited. meanwhile, gaskins got a positive i.d. on the human remains found out past blacksville. it was skylar.