Quoting from one of the many voluminous books that one has to go through to appear for the CFA exams:
The investor needs to be intimately familiar with the investment process of the manager's organization(where manager means fund manager which is what Madoff was).. Futher .. Before selecting a manager the plan sponsor needs to spend time asking questions of several key people in the organization.
Clearly the funds and rich individuals who invested with Madoff , missed this para.
As the saying goes "A fool and his money will be soon parted".
I know this might sound like kicking a guy when he is down, but when you are dealing with the kind of money these people were, surely they should have asked more questions.
On a slightly unrelated note, I read an article of how a wealthy Jewish community in Chicago was devastated by the Madoff scandal.
It brought to mind certain thoughts I have had in the past.
For some reason we tend to trust somebody solely on the basis that they belong to the same community. I guess its human top an extent, to be a little suspicious of the unknown.
But it is quite illogical to base our trust on which community someone belongs to.
Scoundrels comes in all shapes sizes , colors , speak many different tongues and worship many different Gods.