Agatha Christie Wiki

AKA Count Stepanov; Monsieur Krassine. One of the few characters to appear in the adventures of different sleuths, Ivanovitch first appeared in a Tommy and Tuppence book, where as Count Stepanov he was a member of a revolutionary Bolshevist gang. Later, in a Hercule Poirot novel, he posed as Monsieur Krassine, a member of the Russian Embassy in Paris, where he worked with Olga Demiroff in the Heart of Fire ruby theft. Ivanovitch as “a little man with a face like a rat ... In an empire where rats ruled he was king of the rats.” The Secret Adversary; The Mystery of the Blue Train.