In the level Traditions of the Trade, as soon as you enter the building if you go to the right of the staircase you will see a set of double doors. Go through them and pick the second set of double doors with a sign that says hotel wing closed. Once you do that go to room 106 or any of the other rooms around there closed off by police. Go into that room and walk into the bathroom then go into first person view and look in the mirror and you will see a ghost.