everybody kept giving us the name riley gaul. use of their relationship, because they had seen the way that riley had treated her, the way he'd talk to her. >> reporter: so the knox county sheriff's department pays him a visit. >> he didn't say a whole lot. >> reporter: riley takes to social media to publically mourn his lost love. "rest easy now, sweetheart. i love you forever and always." >> what stood out to me from these tweets immediately was the repetitive nature of him saying, "i love you. i love you. i love you." if you just saw that, if you just saw that, you would think that this was an ex-boyfriend who just lost his first love. >> reporter: emma's friends are devastated. >> i was confused. all i knew is she was dead and there was nothing i could do. >> it didn't register in my mind. no one would expect our emma to be dead. >> reporter: a town in mourning, honoring emma with a candlelight vigil. >> students will be gathering at central high school tonight to remember a classmate who recently died. >> reporter: her fellow