NEW YORK (CNNfn) - Additional charges are expected to be filed Thursday in the government's case against former Enron Chief Financial Officer Andy Fastow.

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The government already filed a 78-account indictment against Fastow half a year ago. He has pleaded not guilty. The new charges may expand upon those charges and on charges against two others connected with him.

Prosecutors allege that Fastow was the mastermind behind a scheme to defraud Enron, its shareholders and others through special purpose entities that helped the company hide roughly $1 billion in debt before it went bankrupt in December 2001.

Authorities are also considering bringing charges against three former Enron finance executives including Lea Fastow, Fastow's wife, and two other former executives from the ousted CFO's global finance unit.

A spokesman for the Fastows declined to comment.

Separately, charges may be filed against as many as five former Enron Broadband employees. The Houston Chronicle reported the specific charges would probably be largely in connection with statements made at a meeting with analysts in 2000 and could include insider trading, stock fraud and money laundering.

The new broadband indictment includes charges against the division's chief Ken Rice, two other top executives and two technology executives at the unit, one of the sources said. A lawyer for Rice did not immediately return a call seeking comment.

Enron, once a heralded energy conglomerate, became synonymous with corporate disaster when it filed for bankruptcy after its stock plummeted in the preceding months. Several investigations into the company's behavior continue.  

--from CNNfn reporter Jen Rogers and producer Brett Gering, wire reports