Lois Duncan was an American author known for her young adult novels, particularly in the suspense and thriller genres. Born on April 28, 1934, in Hastings, New Mexico, she began her writing career in the 1950s and gained popularity with books like I Know What You Did Last Summer and Killing Mr. Griffin. Her works often explore themes of adolescence, identity, and the consequences of choices. In addition to her fiction, Duncan was an advocate for children's rights and education. She became an outspoken critic of violence in media after the tragic death of her daughter, Kaitlyn, in 1989. Duncan's legacy continues to influence young adult literature and discussions about youth safety.