If a trail of crushed fruit down the hallway isn't enough to get Stephan's attention, I don't know what would. I'm also not sure if my third floor neighbors would even notice the difference. As soon as I get Stella back--and she's calm again--you need to meet her. She'll fall asleep in your hand if you're still enough.
...I don't want to involve the police yet. Besides, it looks like Stella might have been found by one of our other neighbors. The real issue at hand is why the management isn't concerned that his tenants' homes are being broken into and left in a state of disarray.