One of the guest bedrooms in the Mansion has a walk-in closet. In that closet is a full-length mirror. You turn on the light in the closet in order to get a better look at your reflection.
Your reflection looks nothing like you, but, rather, is a person of the opposite sex of the same height as you, wearing different clothes. The movements and gestures of that person match your own. The reflection of your identifying papers will show the identity of the person in the mirror. You may be able to track down that person.