Witnesses testifying against him had recently appeared in front of a specially convened grand jury, with reports suggesting prosecutors were looking to have charges filed by July 4.

Likely charges would include conspiracy for helping to hide the true financial position of Enron.

Former CEO Jeffrey Skilling and top accountant Richard Causey are waiting to be tried on charges of, fraud and insider trading.

Enron finance chief Andrew Fastow pleaded guilty in January to two counts of conspiracy, in turn becoming the most senior Enron executive to roll over and become a prosecution witness.