What else should I do here?

Hint 1 of 6:

Maybe you should see if Christian Ritter's journal is on the shelf.

Hint 2 of 6:

Did you check the "Case Book" section?

Hint 3 of 6:

Did you notice the desk?

Hint 4 of 6:

I don't think that phone is just there for ornamental purposes.

Hint 5 of 6:

Is there someone Grace could call for assistance?

Hint 6 of 6:

Did you check your inventory?