Why does Juliet feel responsible for Beatrice's murder in the novel, Transcription?

It is Juliet who convinces Beatrice, Mrs. Scaife's maid, to allow her to search Scaife's things while she is away. When Juliet accidentally leaves her purse in Mrs. Scaife's house, however, Beatrice attempts to return it to her the next day, but she is murdered on the way, her body stuffed in the coal hole at the Carlton Club. Juliet is consumed with guilt because she feels that this event is her fault... had she not left her handbag, Beatrice would almost certainly still be alive