Cell phone camera images are date stamped and useful if no health or safety code violations show up.

He put cameras up facing the outside, and the day after Thanksgiving he vanished.I eventually found a relative who informed he me that he left the county and is now living with a relative to get the help he needs. 

If that still doesn't clear your mind, then you can go with a PM, or you can wait outside while they look and film them entering & leaving the house as proof you were outside, or get cameras outside to independently film everything that's going on so you can have proof you were outside, etc. 

Be Obsessed or Be Average - Grant Cardone Podcast that have fired me up the last month are: Episode 749 on bigger pockets with Josh Janus and episode 761 with Yamundow Camera.

It is critical to have evidence quality imagery (faces need to be clearly identifiable at normal distance); plenty of NVR storage...at least two weeks continuous recording of all cameras; POE power supply; easy, high quality mobile app available; and an intuitive, user friendly, remote access capability.

If I were doing this I'd also get a ring door bell or another camera in case something goes wrong I have video of exactly who entered the property.

We manage 7 remotely in different cities with an 8th in progress.....we made a ton of little mistakes early on.....it helps a ton being tech savvy....setting up ring camera, water leak monitor, pms, emails workflows, etc.I have a book half written on remote managing properties 7 properties on less than 15 mins a day.

Then put up a blink camera on the drive and when you get a notification that he has left on the camera just go to the thermostat app and turn his air off or up. 

I also have camera in the backyard , from yard and at the door. 

Depending on property size, security cameras may not be a bad idea anyways.