king county prosecuting attorneys kristin richardson and carla carlstrom. >> he had not done well onhe point of view gra polygra polygraph and they wanted him to take another. >> it must have a big red flag for police. >> i think whenever someone flunks a polygraph test, police get concerned, suspicious, and often want to go at that person harder and find out why. >> reporter: greg may have lawyered up, but detectives used those polygraph results to turn up the pressure. they told your sister you failed the polygraph test? >> yes. >> reporter: why? >> i guess they wanted to turn her against me. >> reporter: lots of people in town were turning in that direction. in those first dark weeks after sandi went missing, her dear friend, vicky, started to think greg was somehow involved. >> the police came to me and said certain things that would lead you to think that maybe he did it. >> reporter: what did they tell you that made you start to suspect greg? >> he didn't pass the test. that there was -- there was people that -- the work heart had heard them fighting. just enough that it's like