I watched a film, probably sometime in the 90's about a teenage girl who is murdered by another teenage girl. I think it was in a Forrest or something and it was definitely set in America. The murders mother finds out about what her daughter has done as she finds a woolen jumper in her daughters bag, and as her daughter is allergic, she knows it can't be hers. It turns out that it belongs to murdered girl. Also on the night of the murder, her daughter came back with a bleeding ear, where her earring was pulled out in a struggle. Very vague but that's all I can remember and it has driven me mad for years.