Although Fastow has not been charged with any crimes, his role was outlined in a plea agreement with former subordinate Michael J. Kopper, 37, who admitted to wire fraud and money laundering. Kopper agreed to forfeit $12 million in profits and cooperate with prosecutors.
Federal authorities said they will seek to seize $23.6 million that they say Kopper passed on to Fastow's family and others, as well as a nearly 12,000-square-foot mansion Fastow was building in a Houston suburb, through civil forfeiture proceedings.
"We will chase the money and seek to get it back," vowed a senior Justice Department official who asked not to be identified. "This money is treated as tainted."
Court documents also show that Fastow's wife, Lea, was paid $54,000 as an administrative assistant in one of the questionable partnerships. One legal expert said federal authorities may be applying pressure on Fastow by threatening prosecution of his wife.
But the Justice Department official said there is not believed to have been any discussion at this point of bringing criminal charges against Lea Fastow. A spokesman for Fastow declined to comment.
Experts said the plea bargain with Kopper is a significant advance for the government because he can help prosecutors build a case against Fastow, who is believed to have orchestrated the off-the-books partnerships that lay behind Enron's disintegration.
"This is a substantial break for our investigation," said Leslie Caldwell, head of the Justice Department's Enron task force. "... When someone agrees to cooperate, essentially all of the knowledge they have becomes our knowledge."
The case may go a long way toward cementing Enron critics' allegations that the firm's partnerships were fraudulent entities all along. Key former executives have insisted that the partnerships served legitimate purposes.
In court papers, prosecutors alleged that Fastow, 40, and Kopper deceived investors in the formation and operation of three partnerships from 1997 through July 2001. The details of two of them, known as Chewco and Southampton, had previously been made public. But the third, RADR, contained new details about how the two men went to great lengths to disguise wrongdoing from government regulators and investors.
The partnership was formed to mask Enron's control of electricity-generating windmill farms in California. The scheme involved outside investors buying stakes in the farms, according to court papers. Unknown to investors, Fastow lent money to Kopper, who in turn lent money to personal friends to acquire their stakes.
In a three-year period, the investors earned about $2.7 million, and when the deal was later unwound and Enron bought back the farms, they made an additional $1.8 million, according to the filing.
In a maneuver that occurred in other transactions, the outside investors transferred some of their profits back to Fastow, Kopper and members of their families, according to the document.
The court papers also offered hints as to the government's strategy for pursuing Fastow.
One former prosecutor, for example, said the mention of Lea Fastow in court papers may be designed to send a message to Fastow that his wife will be charged if he does not cooperate.
When junk bond king Michael Milken struck a plea bargain with investigators in the early 1990s over insider-trading allegations, he agreed to plead guilty to securities-law violations in part to shield his brother, Lowell, from prosecution
Fastow "now has to make a Michael Milken-type decision," said Jacob Frenkel, a former prosecutor now in private practice in Washington. "It's possible the message to Andy Fastow is, 'tick, tock, time is running out' " to make a deal.
The government may also have wanted to send a signal that it has extensive evidence against Fastow and would agree to a plea arrangement only if it carried strong penalties, some experts said.