Who is Amber Ekdahl from Ghost Girl: The True Story of a Child in Peril and the Teacher Who Saved Her and what is their importance?

Amber is Jadie's younger sister. Amber turns six during the time period in which the novel was set. Jadie is concerned that Amber will be killed during the year that she is six. When Amber starts kindergarten Jadie refuses to leave her sister in the classroom until Torey separates the two. One day, when Amber hurts herself on the playground, Torey discovers a scar in the shape of a encircled cross on the girl's abdomen. Amber tells Torey that Jadie made the mark on her stomach. She also tells Torey that it was Jadie who killed Jenny the cat. Even after the girls have been taken from their parents, Amber has no knowledge of the abuse. According to information in the novel, Amber apparently blocked her memories of the abuse out of her mind so completely that she is unable to remember anything that might have happened to her.