Kenneth Lay, the founder of Enron Corp. who ascended to the pinnacle of American business only to tumble into disgrace, died of a heart attack on Wednesday. He was 64.

Lay, 64, faced the prospect of the rest of his life in prison after his conviction May 25 of fraud and conspiracy in one of the biggest debacles in American corporate history.

Dr. Robert Kurtzman, Mesa County Coroner, said his autopsy showed Lay died of heart disease while on vacation in Aspen, Colo.

Lay ascended from near-poverty as a minister’s son in Missouri to the pinnacle of corporate America. He was considered a visionary who had President Bush’s ear during Enron’s halcyon days, but his reputation and monumental wealth shattered with that of his company. He spent his last years optimistically insisting he was no criminal, even after he became a felon.

“I guess when you’re facing the rest of your life in jail and in your heart you know you’re an innocent man, I guess it’s too much to bear,” said close friend Willie Alexander.

Lay had stayed out of the public eye since he and former Enron CEO Jeffrey Skilling were convicted of fraud and conspiracy for lying to employees and investors about Enron’s financial health.

Lay, who described himself as naturally optimistic, displayed no signs of ill health throughout the grueling four-month trial that started Jan. 30. His lead lawyer, Michael Ramsey, was sidelined for several weeks during the trial because of heart problems.

Kurtzman said the autopsy revealed that Lay had a heart attack in the past.

“It’s a very sad ending for the whole Lay family saga. There are very few people of his age and abilities who flew as high or who fell so low,” said John Olson, an analyst who angered Lay with his skeptical takes on Enron’s often indecipherable financial reports.

Along with fraud and conspiracy charges, Lay also was convicted in a separate federal trial of bank fraud and making false statements to banks. Those charges related to his personal finances.

Lay was scheduled to be sentenced Oct. 23, along with Skilling, who also faces a long prison term.

Skilling, reached by telephone at his home in Houston, told The Associated Press that he was aware of Lay’s death.

“No, I don’t have any comment,” he said quietly. But his lawyer, Daniel Petrocelli, described Skilling as “devastated.”

“Jeff and Ken worked closely over the years, and Jeff will miss him dearly,” Petrocelli said.

Lay led Enron’s meteoric rise from a staid natural gas pipeline company formed by a 1985 merger to an energy and trading conglomerate that reached No. 7 on the Fortune 500 in 2000 and claimed $101 billion in annual revenues. Lay traveled in the highest business and political circles, lived an extravagant lifestyle and gave generously — as much as $6.1 million in 2001.

Lay’s clout evaporated when Enron spiraled into bankruptcy protection in December 2001. The crash obliterated Enron’s more than $60 billion in market value and thousands of jobs, and Lay was pushed out as chairman and CEO in January 2002.

While Ken Lay's death ends part of the criminal case against him, there are a couple of issues to resolve. First, the government has filed a motion seeking at least $43 million in Lay's assets. Prosecutors claim he illegally benefited from a line of credit he used at Enron. They also seek money he received in bonuses. The government must decide whether to continue to seek forfeiture of those assets from Lay's estate. Second, there's the question of what Lay's death will mean to further proceedings against former Enron CEO Jeffrey Skilling. His lawyers might seek to delay sentencing. -- Pete Williams, NBC Justice Correspondent Read more in The Daily Nightly

The government launched a widespread fraud investigation that enveloped Enron’s finance, trading, broadband and retail energy units. The probe amassed 16 guilty pleas from ex-executives, eight of whom testified against Skilling and Lay during their trial.

Lay and Skilling insisted no fraud occurred at Enron except from a few employees who skimmed money behind their backs. Jurors were unconvinced.

“I loved Enron very much. And I loved Enron’s employees very much. I spent half my professional life running Enron. I think we built a great company. We changed energy markets around the world,” Lay testified during the trial.

Prosecutors in Lay’s trial declined comment Wednesday, both on his death and what may become of their effort to seek $43.5 million from Lay that they say he pocketed as part of the conspiracy. The government is seeking $139.3 million from Skilling.

Lay’s death will not affect the government’s case against Skilling, who will appeal his convictions, Petrocelli said.

The Pitkin, Colo., Sheriff’s Department said officers were called to Lay’s house in Old Snowmass, Colo., shortly after 1 a.m. MDT (3 a.m. EDT). He was taken to Aspen Valley Hospital, where he died at 3:11 a.m., said Pat Worcester, executive assistant to the Aspen hospital’s chief executive.

Pastor Steve Wende of Houston’s First United Methodist Church, said Lay seemed healthy when he attended services in Houston on Sunday, and even believed God may have had a purpose for him in prison.

“He was very much at peace with his future, he had a perspective on what had happened, he even bore no ill will for the jury or all of the people who might want to say terrible things about him,” Wende said.

“Apparently, his heart simply gave out,” Wende said.

Before Enron became a scandal-tainted punchline, the company was the single largest contributor to President Bush, who nicknamed Lay “Kenny Boy.” Lay said he was closer to the president’s father, former President George H.W. Bush. He kept a framed photo of himself with a smiling elder Bush and former First Lady Barbara Bush.

“It was sad to hear the news of the death of someone I considered a friend,” the elder Bush said in a statement Wednesday.

But White House press secretary Tony Snow said Wednesday he hadn’t discussed Lay’s death with the president.

“The president has described Ken Lay as an acquaintance. And many of the president’s acquaintances have passed on during his time in office,” Snow said.

During the trial Lay had been expected to charm jurors, but instead came across as irritable and combative.

Lay defended his personal spending, including a $200,000 yacht for Linda Lay’s birthday party in early 2001, despite $100 million in personal debt. He told jurors it was “difficult to turn off that lifestyle like a spigot.”

Lay also defended how he borrowed more than $70 million from Enron in 2001 — even as the company was spiraling — and repaid most of those loans with company stock.

“I wanted very badly to believe what they were saying,” juror Wendy Vaughan said after the verdicts were announced. “There were places in the testimony I felt their character was questionable.”

Lay was born in Tyrone, Mo. and spent his childhood helping his family make ends meet. His father ran a general store and sold stoves until he became a minister, and Lay delivered newspapers and mowed lawns. He attended the University of Missouri, found his calling in economics, and went to work at Exxon Mobil Corp.’s predecessor, Humble Oil & Refining.

Lay is survived by his wife, five children and stepchildren and 12 grandchildren.

The unexpected death of convicted Enron founder Kenneth Lay may end up saving his family tens of millions of dollars in government fines. Lay’s massive heart attack should keep prosecutors from seizing the $43.5 million in assets they had demanded last Friday. How come Ken Lay’s estate gets to keep that money?

Now that he’s dead, he’s no longer a criminal. The principle of “abatement” lets a defendant off the hook for a conviction if he happens to die before getting through at least one round of appeals. If he doesn’t get a chance to file an appeal, he’s missed out on an integral part of the legal process, so he gets the benefit of the doubt. In other words, he’s innocent until proven guilty, and then proven guilty again. Since Ken Lay died before he could appeal, the courts will abate his conviction and all the punishments he would have received.

A defendant doesn’t even have to assert his innocence or file an appeal to score an abatement. If he dies within the 30-day window allowed for appeals, he gets his conviction abated no matter what. That means Ken Lay would still have had his abatement if he’d raced out of the courtroom and shot himself just moments after hearing the original verdict in his case.

Most states and almost every circuit in the federal system treat abatements the same way: A defendant’s conviction disappears, and his estate can ignore any outstanding fines against him. (If the defendant had already paid some fines, the government gets to keep that money.) The 3rd Circuit provides the exception to this rule: There, a defendant keeps his conviction when he dies. His case freezes—there are no further punishments, but also no opportunities for appeal.

The federal rule of abatement can also have a big impact on outstanding civil suits. In general, a plaintiff can go ahead and sue a dead man by subbing in the man’s estate as the defendant in the case. (This won’t work for some kinds of lawsuits—a dead man can’t be liable for defamation, for example.) But if the dead man’s conviction had been abated, the plaintiffs wouldn’t be able to use it against him in civil court. That means the plaintiffs against Ken Lay would have to argue the facts of the criminal case all over again in front of a civil judge.

There’s a catch: Because Lay and Jeffrey Skilling may be named as co-defendants on the civil suits—and because Skilling is alive, well, and unabated—a judge might decide to let the plaintiff lawyers use the Skilling conviction without rearguing the case against Lay.