I don't have enough information to determine exactly who Judith Kay is. She could be an ordinary woman who gets caught up in an extraordinary situation involving the mirror.
Kay might be the person who created this unique fan fiction world. In the context of the story, Kay could also be a protagonist or an important side - character. Maybe Kay is an archaeologist who discovers the mummy and experiences the unexpected comfort. Or Kay could be a local guide in an area with mummy - related legends, and through some adventure, the comfort aspect comes into play. Without reading the fan fiction, it's hard to be certain.
I don't know for sure, but she is probably the main character in the 'betty knox ghost story'. Since it's named after her, she must be the one who has some kind of experience with the ghost.
Betty Broderick was a woman who was deeply wronged in her marriage. She felt scorned when her husband had an affair and left her for another woman. Her story is one of a woman pushed to the edge by the actions and neglect of her partner.
The Kay Scarpetta novels are typically published in a certain chronological order. For example, 'Postmortem' is one of the early ones in the series. But to get the full and accurate order, it's best to check the official Patricia Cornwell website or a reliable bookseller's website.
I'm not entirely sure which is the absolute latest Kay Scarpetta novel at the moment. But Patricia Cornwell, the author, has been writing these novels for a long time. You can check her official website or major book retailers to find out the most recent one. Usually, the new novels in this series keep up with the modern forensic techniques and also deal with the personal and professional challenges that Kay Scarpetta faces in her life.