You can install a camera.  

I also have the Nest smoke and carbon monoxide detectors (State requires carbon monoxide detectors) CO2 detectors give you peace of mind anyway so you may want to consider that at the top of your list.I have also set up my own portable security cameras when I don't have tenants.

We even bought a small compact camera with a zoom to take pictures for them.

I have a video camera.

They used infrared cameras to detect this information.

There are weapons lying around, marijuana everywhere, all the windows are covered, he has cameras outside the house, ect.

I think BP needs to send out camera crews to investors projects and start producing more video content!

So, I went back to focusing on my career as a nanny, which I've done for 11 years.

while I use a software checklist tied to my PM software now, I used to walk the property with a checklist by room with categories to check (paint, floor, fixtures, blinds, etc.) and camera..  

I had a camera with a good flash and I took several pictures that shows a lot.