The movie is a cleaner version of what had happened to Missy Avila. There was a book written shortly after the murder, however, according to Missy's family on their Facebook page, it isn't accurate. They are coming out with a documentary to tell the true events that took place.
Tiffani Thiessen, who plays Jenny Monroe said on her question-and-answer blog that playing Jenny was the hardest role she ever played in her career and it was the most emotionally and physically exhausting role for her.
In the movie, Jean asks Ellen to move out, but this did not happen in real life. Mrs. Avila never asked Karen Severson to move out and also let her stay in Missy's room and even wear her clothes.
Jenny sports a braid in her hair when she has it half-up. After her death, Ellen starts braiding her hair the same way Jenny did, hinting at her obsession.