How do I get inside Von Zell's room?

Hint 1 of 17:

Let's review what we know so far.

Hint 2 of 17:

Gabriel witnessed Von Zell leaving his room and locking the door behind him.

Hint 3 of 17:

Gabriel doesn't have a key.

Hint 4 of 17:

Gabriel isn't carrying anything in his inventory that can pick a lock.

Hint 5 of 17:

The windows *aren't* locked.

Hint 6 of 17:

Sooooooo ... it looks like Gabriel will have to go through a window.

Hint 7 of 17:

Have you figured it out yet?

Hint 8 of 17:

Okay, here's another hint.

Hint 9 of 17:

Preiss is still in the bathroom and, if you've been downstairs, you know that
Hennemann is probably five sheets to the wind by now, so the room is empty.

Hint 10 of 17:

Von Zell's room is right next door to Preiss' room.