I don't know whether you're uninformed or deliberately misleading, but that's entirely wrong. He fell after he confessed his crimes to his kids and they informed the FBI (on 2008-12-10, with his arrest the very next day).

However, people had been informing the SEC with suspicions a decade earlier, as recounted in the book No One Would listen: "Madoff Securities LLC was investigated at least eight times over a 16-year period by the U.S. Securities and Exchange Commission (SEC) and other regulatory authorities."

https://en.wikipedia.org/wiki/No_One_Would_Listen https://en.wikipedia.org/wiki/Madoff_investment_scandal