After you talk to Ewan, go back to your room and see what you can see. The place has been cleaned up, but there are two things here you should look at.
First, notice that the vase is now empty. Click on it to get Nancy to comment.
Second, go look at the window. See anything different?
I missed it too. Look at the windowsill, at the right. That black thing that looks like a pen --
-- is actually a laser pointer, and the logo on it is the same one you saw inside Alec's bag when you were planting that fly-shaped bug. That's suspicious enough that we should go talk to Alec about it.