These guys are in this situation because they do not know where the line is. It is a common wisdom to adult that applies to any part of life.
Never ever lend the money to the people you do not know or trust 100%, unless of course if you just want to help and it does not matter to you whether you will be paid back. Not just with a WG even to your close relatives, family, friends, etc. How many times we have read a story about a family dispute because of this.
Never ever reveal your personal detail, financial detail to anyone ....
I think these guys need to grow up and move on. Alternatively if they have evidence then take them to the court.