Why Kill Amy Stevens?

Amy Stevens is a beautiful,intelligent, kind hearted, generous 17 year old girl who would do anything to protect her family. She volunteers at the homeless shelter and a support clinic. While doing all of this she still manages to keep her relationship with her boyfriend of two years, strong. She has a very good relationship with her parents and sibling. And she makes sure that everyone knows that she is their friend and that they can talk to her about anything and everything. She's the girl every guy wants and what every girl wants to be. Yes, she still has flaws but she shows off her flaws with confidence. She's basically perfect. So why kill Amy Stevens?