They do not believe it was caused by any sort of soil issue. 

Additionally, I look at building code violations and or recent permits issued for the building.

Eventually that end will probably come, and if they move out the investor has the same issue.

Not sure I'd personally buy a property that has a radon issue, but I've worked on large MF deals that build and rent anyway.

Hi - not missing anything, this is a very common issue. 

Call the number on the letter, if you/your parent has trouble with talking to them due to a language issue ask for a translator.

-Tell them that anyone else who moves in at a later date must have a US issued ID (driver's license, ID card etc) and they cannot have any criminal record inline with your preset screening criteria. 

This will be helpful to hopefully offset some of the lad cost issues I am facing right now. 

Part of the issue was we were bundling trades with our contractor.

As a Cap Rate is indicative of the risk involved in owning the property, you want to focus on doing things that make your investment less risky if a bank ever had to take over.You can make your investment less risky by doing some of the following things:- Convert all month-to-month tenants to annual leases- Implement strict minimum rental criteria- Add security cameras- Make large capital and preventative improvements (fix drainage issues, install water pressure regulators, replace old HVACs...you get the picture)- Essentially, prove with action that you are caring for the property on a long-term basisThe only way this is effective is if you document everything you are doing as well.