They'll deny they ever smoked in there and you aren't able to put cameras in there either.

In a nutshell.Purchase Price 90,000Interest Rate 5.5%Down payment 20% 18,000Closing Cost 7,446 (includes prepaid taxes, insurance for 1 year, appraisal, loan fees)Inspection 600 (includes home inspection, camera scoping and cleaning the sewer line)Property Management fee 1100Rent Cert 250Misc repairs 1000Total Invested 28,396Projected rent 1100/monthProjected cash flow 188.19/month for a 7.95% CoC RoI (this is after all expenses like PM fees, Insurance, Taxes, mortgage and vacancy, maintenance, Cap Ex at 5% for each)I know it's not a home run but for my first property to get into and prove to the people I work with that I'm serious about investing I am OK with the outcome. 

Put up video cameras and big signs that say the area is under surveillance.

Landlord set up and control of the property Wi-Fi can provide many advantages, from becoming a small but steady source of extra revenue, to enhancing security (remote control and recording of gates, entries, exterior building & common area cameras); to saving time (remote entry control & rekeying of door codes); to saving money on maintenance (through instant water leak notification & advance indications of appliance malfunction); to saving both tenant and Landlord money on energy usage through remote timing and/or turn on/off all or some lights, appliances and devices;  to ensuring compliance with lease agreements (real time notice of smoking on property, excess people on property), and so much more.Did you know that for $300 (plus installation), a landlord can install a device that will record and report in real time the energy consumption of pretty much any electrical device on the property (https://sense.com/ ) ( https://www.schneider-electric.us/en/home/smart-home/wiser/wiser-app/ ).

I bought a FLIR One Camera that will provide infrared read out information.

I had a 4-camera system put on my house (professionally installed) with a 2-terabyte DVR and it only cost me $1200 cash.

The spirit shines or illuminates on a flashlight like the one from a camera.5/ Call the ExpertIf you have your journal ready with enough evidences, it’s time to call a Paranormal or parapsychologist expert for further investigation.6/ Perform a house cleansings:If you're a Christ Follower and empowered by the Holy Spirit, the authority of Christ (Luke 10:17-20), you could easily perform a spiritual house cleansing.

@John Mark Pollard:Hire a certified septic inspector that uses a camera to inspect a septic system.  

I hope you're able to get things figured out; maybe inquire with a neighbor if they have a camera facing the property -- might be able to get a clearer idea of what actually happened. 

No one could possible pay licensing fees, insurance, agent commissions, software, rent, vendors vetting, accounting, website, advertising, cameras, phones, internet, etc for $79/month.