Alleged swindler Bernard Madoff was in US federal court Tuesday for a hearing before the judge who is expected to hear the financier's guilty plea later this week. Madoff, 70, was brought to the federal courthouse in lower Manhattan under tight security from the Upper East Side apartment where he has been under house arrest since December. According to investigators, Madoff estimated he bilked investors, including an array of Jewish individuals and institutions from Nobel laureate Elie Wiesel to Yeshiva University, out of as much as $50 billion in what may be the largest Ponzi scheme of its kind. Madoff faces a single securities fraud count that could carry a maximum 20-year sentence but has not been formally indicted. He has cooperated with authorities and is expected to plead guilty at a hearing scheduled for Thursday morning, just ahead of a legal deadline for prosecutors to file an indictment that would lead to a jury trial. The financier has not spoken publicly about his guilt or innocence, but reached an agreement in February with the US Securities and Exchange Commission on civil securities fraud charges in which he did not admit or deny guilt but acknowledged allegations that his business was a sham. At least 25 stricken investors have requested permission to speak at Thursday's hearing before district court judge Denny Chin. Chin was due to hear arguments from prosecutors late Tuesday afternoon concerning potential conflicts of interest involving Madoff's attorney, Ira Sorkin, including his prior representation of clients who might be called to testify against Madoff in any potential jury trial. According to a letter submitted to the court by prosecutors, Sorkin's parents also invested approximately $900,000 with Madoff - money that has since been placed in trust for Sorkin's sons. Sorkin's name appeared on a list filed in bankruptcy court last month in proceedings to liquidate the remnants of Madoff's firm, Bernard L. Madoff Investment Securities. He said at the time he was not personally a victim of the swindle.