You could always invest in some cameras.

I'd double check vents, and perhaps take a snake camera to the drains within the kitchen.  

And they are not dealing anything and anyway I have no proof of any wrong doing on their side.I installed a 24hrs surveillance system with a camera pointing directly to the entrance of their and 3 other units.

Or always on the surveillance list.

Installing items and deploying techniques like electronic locks, cameras, proper guest screening, listing descriptions, and knowing how each platform operates is key.

It would be great if your witness could also video record it all.Your mission:  Ignore her completely, as you walk though and write everything down that relates to the walk through, and say it out loud for the camera.  

Go with a friend and a police officer with video camera and have your friend video you entering the property, videoing each room and then taping you removing all food from the premises.

I had the plumber come out and he showed me with the scope (Camera) the sewer line was broken 8 feet under the foundation.

This is easily accomplished if you want to be using your phone or you can just program the time and date into your camera 

She actually didn't put up any fight and when I got the unit back I went in with a camera just in case but it was in pretty good shape- she got most of her deposit back even!