In a stunning rebuke, the Securities and Exchange Commission Chairman Christopher Cox blamed his career regulators for a decade-long failure to investigate Wall Street money manager Bernard L. Madoff, now accused of running one of the largest pyramid schemes ever.

On Tuesday night, Cox ordered an internal investigation of what went wrong and offered a scathing critique of the conduct of his staff attorneys. He said they never bothered to seek a formal commission-approved investigation that would have forced Madoff to surrender vital information under subpoena. Instead, the staff relied on information voluntarily produced by Madoff and his firm.