Former U.S. Securities and Exchange Commission chairmen and directors were generally unaware that staff were probing Bernard Madoff until the former financier was arrested in December 2008 for running a $65 billion Ponzi scheme, a federal watchdog said in a report released on Friday. The report underscores the disconnection between senior officials and their employees, who often lacked the experience necessary to follow up on leads and understand the magnitude of their investigation. Former Chairmen Christopher Cox, William Donaldson and Arthur Levitt, former director of enforcement Linda Thomsen and former director of examinations and compliance, Lori Richards, did not play...