In the novella The Mystery of the Spanish Chest, Major Charles Rich is a friend of Arnold Clayton and his wife Margharita. After the dead body of Arnold was found in a large chest at the home of Major Rich, Rich was arrested he had opportunity and motive. As for motive, it was believed (correctly) that he is in love with Margharita Clayton.
Charles Rich is a reworking of the character Major Jack Rich from The Mystery of the Baghdad Chest, the short story from which the novella was expanded.