HOUSTON — At its heart, the biggest criminal case to emerge from the largest corporate scandal of recent years comes down to whether Enron Corp.'s top two former executives lied.

Enron founder Kenneth Lay and his hand-picked successor as CEO, Jeffrey Skilling, are to go on trial Jan. 30 as alleged purveyors of deceit, more than four years after the company became synonymous with corporate greed and wrongdoing.

Before its 2001 fall, Enron ranked seventh on the Fortune 500, posting billions in revenue and oozing prestige, money and swagger. Lay and Skilling were the embodiment of it all. But when relentless investigations exposed inflated profits and billions in debt hidden in off-the-books financial structures, investors fled and the company crumbled.

The question for a dozen jurors to answer is whether Lay and Skilling knew of Enron's rot when they repeatedly declared publicly that all was well or would improve.

"The crimes alleged at Enron were not the acts of a few greedy senior executives but truly was an indictment of almost the entire corporate culture," said Robert Mintz, a former federal prosecutor who has followed the Enron saga since the energy company went bankrupt in December 2001.

The government alleges Lay and Skilling conspired with minions to mislead investors, analysts, auditors and employees through false or sanitized financial statements, empty hype and shady accounting maneuvers in finance, broadband, trading and retail energy units.

The indictment alleges Skilling knew Enron's business units turned to accounting tricks to please Wall Street while he pocketed millions from sales of inflated shares.

Prosecutors allege further that Lay perpetuated the ruse after he resumed as CEO upon Skilling's abrupt August 2001 resignation.

Skilling faces 35 counts of conspiracy, fraud, lying to auditors and insider trading. Lay faces seven counts of conspiracy and fraud, focusing mostly on his actions after Skilling quit. Both have pleaded not guilty and have said repeatedly they were not involved in any wrongdoing.

In a recent interview with the Associated Press, Skilling said he's convinced Enron wasn't rife with corruption as it's been portrayed in the past four-plus years. He also said it's been difficult to watch a string of his former friends and colleagues plead guilty to crimes while others fearful of being indicted avoid him.

"I loved Enron. I loved that company. I built that company," he said.

The trial, expected to last about four months, could be an endurance test for jurors and a challenge for prosecutors to keep it simple, said Ross Albert, a former federal prosecutor.

"If the government cannot explain what happened at Enron and why it was wrong in terms a jury of 12 lay persons can understand, then the government will likely fail to obtain convictions," Albert said.

But Samuel Buell, a former federal prosecutor with the Justice Department's Enron Task Force who now teaches at the University of Texas School of Law, said, "Once you put all these transactions together and you understand how they work together to further an objective — that was designed to present a picture of the company that did not match reality — it's not that complicated."

In a speech last month to Houston business and academic leaders, Lay indicated that the defense teams intend to try to exonerate the company along with their clients, saying that Enron wasn't rife with corruption, and that the deals, partnerships and financial structures outlined in the indictment were legitimate.

Such activities include holding portions of profits in reserves and off-the-books structures and partnerships that carry debt or assets.

Lay said in his speech that the government's investigation targets normal daily business activities common in publicly traded companies across the country.

Gary Brown, former special counsel for the Senate Committee on Governmental Affairs during its investigation of Enron's collapse, said such an approach by the defense could be risky.

Sixteen former Enron executives have pleaded guilty to crimes, including securities fraud, insider trading and conspiracy, Brown noted. They include former chief accounting officer Richard Causey, who was to go to trial alongside Lay and Skilling until he pleaded guilty last month; former chief financial officer Andrew Fastow; and former heads of retail energy, broadband and investor relations.

Four former Merrill Lynch & Co. executives and a former midlevel Enron finance executive are in prison after a jury convicted them of helping push through a loan to Enron disguised as a sale.

And, Merrill Lynch, JP Morgan Chase, Citigroup and the Canadian Imperial Bank of Commerce have paid the SEC nearly $400 million to settle allegations that they helped Enron manipulate financial statements and mislead investors. JP Morgan, Citigroup and CIBC also have paid $6.6 billion to settle similar allegations in a conglomerate of Enron shareholder lawsuits.

However, the government has some bruises.

The U.S. Supreme Court in June overturned the 2002 obstruction of justice conviction of former Enron auditor Arthur Andersen LLP, accused of destroying tons of Enron-related documents to thwart an SEC investigation. The justices unanimously ruled that vague jury instructions proposed by prosecutors allowed jurors to convict without finding criminal intent existed.

Last month, David Duncan, former top Enron auditor for Andersen, withdrew his guilty plea to obstruction.

A former in-house Enron accountant tried alongside a colleague and the Merrill Lynch executives was acquitted. And in July, a three-month trial of five former Enron broadband executives ended with some acquittals and jurors hung on other charges, so those defendants will be tried in three cases later this year.