From 1992 - 2008 the SEC conducted five separate investigations of Bernard L. Madoff Investment Securities after receiving numerous credible tips that Madoff was perpetrating a Ponzi scheme. Despite not having purchased a single share of stock in 13 years, each of the five SEC investigations failed to discover that Madoff had not purchased a single share of stock in 13 years. Question: How could the SEC investigators fail to uncover Madoff's Ponzi scheme when it is such a simple fraud to uncover? Answer: The SEC made some serious investigative mistakes, especially some involving interviews with Madoff. Many an investigation is completely blown because of mistakes made when interviewing the suspect The SEC investigators made two critical mistakes when interviewing Madoff: 1. They failed to control the flow of information during the interview. For example, the SEC investigator asked Madoff a question to which Madoff responded with a question. The SEC investigator responded to Madoff's question and Madoff then asked another question. Just like that, Madoff is asking all of the questions and the SEC investigator is providing all of the answers! An effective interviewer maintains control of the interview by asking the questions and insisting that the suspect answer the questions