The US Securities and Exchange Commission has been slammed by its inspector general, David Kotz, for failing to uncover Bernard Madoff's $65bn (£40bn) Ponzi Scheme earlier, after a report reveals that the regulator received several warnings between 1998-2008. Madoff, a former fund manager, was sentenced to 150 years in jail in June after confessing to his fraudulent Ponzi scheme in December. In a report on the Madoff investigation, Kotz said: 'Despite three examinations and two investigations being conducted, a thorough and competent investigation of examination was never performed'. Although there was speculation that the relationship and marriage of the SEC's former assistant director, Eric Swanson, and Shana Madoff, Bernard Madoff's niece, had prevented the Ponzi scheme from being uncovered, Kotz establishes in his report that it was the lack of action taken by inexperienced investigators. Kotz noted: 'When Madoff provided evasive or contradictory answers to important questions in testimony, they simply accepted as plausible his explanations.' The report highlights that one Boston accountant, Harry Markopolis, had written to the SEC on multiple occasions prior to Madoff's arrest to alert the regulator of the fraud. In light of the Madoff scam, Mary Schapiro, the SEC chairman who replaced Christopher Cox earlier this year, said that reforms have had to take place at the SEC on 'how [they] regulate markets and protect investors', reports the Times.