and now, julie harper will grow old behind bars, alone. >> that's all for this edition of dateline, i'm natalie morales, thank you for watching. natalie morales, thank >> when my mom came in, she said, fix my hair. where is she? because she isn't funny. and the bottom of my heart, i knew something was really, really wrong. >> you look underneath, and saw what he thought appeared to be blood. ♪ ♪ ♪ >> a high school beauty found that in the desert, bound. >> what did that say to you? >> a great deal of rage by someone. >> he was like your average high school student. tall, clean cut, polite. >> a teenager with two sites. >> he would yell at her. he would be pushing her around. >> a puzzle seemingly solved, then long apart. >> we recorded that conversation, then it was dynamite. >> mckayla was on the ground, and she wasn't really moving. >> to unravel the mystery, investigators would follow a trail through high school hallways, teaming the secrets and schemes. >> the hatred grew more and more and more. >> the whole idea became a horrible idea. a bad idea that went very, very bad. ♪ ♪ ♪ >>