A federal grand jury in New York has indicted five former employees of Bernard Madoff, who was convicted of running a massive, decades-long Ponzi fraud. A Ponzi scheme involves using funds from new investors to make the business appear successful to the original investors. The new funds keep the business solvent, not revenue or profits from the business itself. Madoff pleaded guilty in December 2008 to running a Ponzi scheme that originated in the 1970s and eventually defrauded investors of $17.3 billion, court appointed trustee Irving Picard has estimated. The Wall Street Journal reported Tuesday former Operations Director Daniel Bonventre and \"back office\" employees Annette Bongiorno and Joann \"Jodi\" Crupi were indicted along with former Madoff computer programmers Jerome O\'Hara and George Perez. \"With the new charges we announce today [Monday] against these five previously indicted defendants, the architecture of Madoff\'s house of cards and each defendant\'s alleged role in it becomes clearer,\" U.S. Attorney Preet Bharara said. When he was arrested, Madoff, who was sentenced to 150 years, insisted he had acted alone. However, several former employees of the firm have pleaded guilty to various fraud counts, including Madoff\'s brother Peter. \"We expect to plead not guilty when we have to appear before Judge [Laura Taylor] Swain tomorrow [Tuesday],\" said Roland Riopelle, an attorney representing Bongiorno. Riopelle was the only one of the defendant\'s lawyers to comment on the case, the Journal reported.