Just kill everyone associated with the "marquise" along with the "marquise" himself. Stop playing stupid games and get on with it. Kill him, kill the bitch of an empress, kill everyone else who's aiming for the throne, kill the nobles who refuse to submit. Do a massive purge. Nobody will miss wastes like them anyways.
How come they don't know caesar's face? the soldiers are ok but the guy with the red blazer(?) come on when you guard something in a prominent family place, shouldn't you know important faces?