In the novel Crooked House, Janet Rowe (known as "nannie" to all in the household) was the nanny employed to look after the Leonides’ childre Josephine and Eustace.
Late in the story, nannie was found poisoned with digitalis-laced cocoa. By this time some progress had already been made in the investigation into the murder of Aristide Leonides. Nannie's death brought consternation to the investigators because whoever they suspected was obviously wrong and the killer was still at large among the members of the household.