The False Prince

From Introduction:

Did you hear? The duchess was robbed! Some thief made off with all of her most precious jewellery. It happend right after she got back from pilgrimage in the south. Nobody knows how it could have happened! Her valuables were all hidden away, no one else knew where she kept them. Well, I suppose the servants might have known. Or one of the guests. But they were all nobles themselves, and none of them were strangers. Well, except that strange elven nobleman she met while travelling, the exiled one that she took in because he didn’t have any money. But he wasn’t even there when it happened! I tell you, it’s a right mystery, it is!