Ah, that's right! We can ask her whether you were outside at 3:00 and 3:15! It would have been quite difficult to run into the music room from outside, kill her, and then run back.

Yes...it does seem strange that the objects within this box seem to be objects that could be found around the manor. And rubbing alcohol is not exactly a poison.

The true second item? But why would they need to hide it?