Fingerprints on the Shower Mirror

Even though I grew up in an old house, I haven't had any ghostly experiences of my own until a few months ago. I have lived alone at my Madison apartment for almost a year, and this is where my first ghostly experience occurred.

One day in March, I was taking a shower before I had to go to one of my lab classes. While I was in the shower I heard a squeaking sound, like somebody wiping off the mirror. Since it was very early and I was half asleep, I thought nothing of it until I got out of the shower and noticed fingerprints on the mirror. It was just like somebody had just come in to wipe their fingers on the mirror. The bathroom door was shut tight the entire time, and I would have heard the bathroom door open if somebody happened to come in. Both of the doors to my apartment were locked and had the chains on. I have a cat, but cats don't have fingers, and they can't open doors.

I asked my neighbors if the guy I subleased the apartment had mentioned anything weird going on in the apartment, and they told me that he hadn't. They also assured me that he hadn't done anything evil in the apartment. When I got to school I told a couple of my classmates about it, and they didn't give me any answers either. I don't think they believed me.