It's good to question these sorts of things, but for in the future try to do it in the most constructive way you can. Making accusations isn't constructive.

It's down to people who give money away to do their due diligence but if you want to investigate this sort of thing for your own satisfaction go to person you're suspicious of and ask them first. Good people often admit to wrong doing if you approach it in a positive way, and bad people get instantly defensive. Accusations mean you wont be able to discern one way the other because you'll force a good person to be defensive and give a bad person an opportunity to turn it around on you.

The truth can often be quite complex and it's very unlikely you'll hit the target through assumptions.