Federal prosecutors appear set to file criminal fraud charges Wednesday against Andrew Fastow,

Enron's

former chief financial officer, according to several media reports.

Fastow is expected to turn himself in to authorities at a Houston courthouse early Wednesday morning. He would be the second former Enron executive to face criminal prosecution by the Department of Justice's Enron Task Force.

Last month, Michael Kopper, a former Enron executive and close confidante of Fastow's, pleaded guilty to fraud charges. Kopper's plea agreement all but named Fastow as an unindicted co-conspirator in a plot to defraud Enron shareholders.

It's not known whether any of the charges against Fastow will involve his management of the LJM2 partnership -- the now infamous $394 million fund that played a central role in Enron's strategy of moving ailing assets and big debts off its balance sheet. A Who's Who of Wall Street institutions were investors in LJM2.

None of the charges against Kopper stemmed from his role in LJM2. But

The New York Times

reports that federal prosecutors may charge that Fastow had obtained a secret agreement from Enron to guarantee a profit for LJM2 in its many business dealings with the Fastow-led entity.

In filing a criminal complaint against Fastow, rather than indicting him outright, prosecutors are expected to lay out in some detail the crimes they allege Fastow committee and possibly point fingers at other wrongdoers at Enron.

Prosecutors typically have 30 days after filing a criminal complaint to either formally indict a person or dismiss the charges. It's during that 30-day window that prosecutors will often try to extract, if possible, a plea deal from a defendant.

A spokesman for the Enron taskforce couldn't be reached for comment.