Very cool game and interesting concept, I could see it being expanded into a full game different mysteries that need solving :) The detective mode was a cool idea and I liked fixed-position camera, it fit with the gameplay very well.
I had a couple of issues with UI elements getting stuck open (LMB to skip didn't work sometimes), and personally I felt like it didn't really need the shadow(?) attacking me in each room, it got a little predictable after a while - perhaps that could only happen once you have visited most of the rooms? And maybe add some audio cues to indicate that it's coming.
Overall a very well made game though, good job!