We hope our capital is in safe hands with you.

The other method is to use a “safe harbor”, i.e., the specific procedures laid out by the SEC in Regulation D.  

Maybe also consider if they are "good people" that work in the community and just want a safe place to raise their family. 

If they have money and can compete on pricing, brokers will be the best bet.  

From day one they promote themselves as high-quality, safe, service oriented and experienced.  

That’s the best bet.

If you want to go further, you can use a service like Safely or AutoHost to run background checks.For payments, I’d recommend using a platform like Stripe or Square—they’re secure and easy to set up.

Quote from @An Lan: I am not a professional real estate investor, I just invest in houses as a safe asset and do not choose to rent them out.

Do you need or want monthly cashflow, tax write-offs, betting on appreciation,....   

I’ve been shown no evidence that there was fraud, nor that the sale of the investment opportunity was not in compliance with either the General Exemption for Private Placement or Reg D safe harbor.