Bernard Madoff told a federal court he was "ashamed" and "sorry," but that his massive Ponzi scheme was designed to "satisfy" his "clients." The judge accepted Madoff's guilty plea to 11 felony charges, revoked his bail and sent him to jail to await sentencing on June 16. Madoff cheated 4800 people out of billions of dollars. Is it possible he did it alone? How could the SEC have investigated and found nothing wrong? Is it enough to blame Madoff? What's being done to make sure this doesn't happen again?