A federal grand jury has indicted Kenneth Lay (search), the founder and former chairman of Enron Corp., and the indictment will be unsealed Thursday, sources said.

"I have done nothing wrong, and the indictment is not justified," Lay said in a statement.

Lay, 62, said he would surrender Thursday morning on charges stemming from the company's collapse, two years after the federal government launched its painstaking investigation.

The charges against Lay are expected to focus on how he received warnings about financial trouble in his company and on his public statements to investors and analysts, FOX News has learned. He is expected to be charged with fraud.

Prosecutors from the Justice Department's (search) Enron Task Force presented an indictment to U.S. Magistrate Judge Mary Milloy, sources said. Prosecutors noted "the defendant" would surrender voluntarily. A hearing before Milloy was scheduled for late Thursday morning.

Separately, the Securities and Exchange Commission (search) plans to file civil fraud charges against Lay in Houston on Thursday morning, a source familiar with the matter said.

Lay guided Enron for years, shaping the once-obscure pipeline company into the nation's seventh-largest corporation and a world-leading energy trading concern.

Enron Corp. (search) collapsed in a massive scandal in 2001 after the Wall Street darling's abuse of off-the-books partnerships to hide billions of dollars of debt and inflate profits became known.

The charges come 2-1/2 years after the Justice Department began an investigation which has slowly climbed the corporate ladder to bring criminal charges against 22 former Enron employees, including former Chief Financial Officer Andy Fastow (search), former chief accountant Rick Causey and, most recently, former Chief Executive Jeff Skilling (search).

Skilling and Causey have been charged with multiple counts off insider trading, fraud and lying on Enron financial statements. News reports have speculated that Lay could face similar charges.

The fall of Enron touched off investigations that uncovered widespread financial fraud in corporate America and was followed by scandals that brought down giants such as accountancy Arthur Andersen (search), telecoms giants WorldCom Corp. (search), now MCI, and GlobalCrossing (search) and HealthSouth Corp. (search). 

Those bankruptcies and charges of criminal behavior in the boardroom eroded consumer confidence and helped send world stock markets into a year-long tailspin. In the wake of the scandals, strict new federal laws on corporate governance were enacted.

In a recent interview with the New York Times, Lay accepted responsibility for Enron's demise, but said he had committed no crimes.

He said Fastow, the architect of Enron's financial house of cards, was largely to blame for the company's troubles.

"At our core, regrettably, we had a chief financial officer and a few other people who, in fact, mismanaged the company's balance sheet and finances and enriched themselves in a way that once we got into a stressful environment in the marketplace, the company collapsed," Lay told the Times.

Fastow, who is accused of enriching himself by siphoning off millions from the off-the-books partnerships, has pleaded guilty to fraud and is cooperating with prosecutors in exchange for a 10-year prison sentence that is yet to begin.

His wife Lea, a former assistant treasurer at Enron, has pleaded guilty to filing a false tax return and is slated to start a one-year jail sentence next week.

Skilling and Causey have pleaded not guilty and currently are free on bail.

Lay was Enron's chief executive for most of the company's history, but handed the post to Skilling in February 2001. Skilling suddenly resigned in August 2001 Lay resumed as CEO until he quit in January 2002.

Lay told the Times his personal fortune once stood at $400 million, but had dropped below $20 million because most of his holdings were in now worthless Enron stock.

Reuters and the Associated Press contributed to this report.