Who is Leona Gaites from Sweet and Deadly and what is their importance?

Leona Gaites, once Dr. Linton's nurse, is found dead on Catherine's property at the beginning of the novel. She wasn't a a very nice person, and Catherine always believed that she didn't like children. After Leona's death, Catherine learns that she was blackmailing residents of Lowfield, and that she was also performing abortions with medical equipment stolen from Dr. Linton's office.