He was the multimillionaire heir to one of the most fabluous estates in the Philadelphia region - the roughly 600 acres of rolling hills and horse stables near Newtown Square known as Foxcatcher Farm, anchored by a stately Georgian-style mansion called Liseter Hall.

But in the end, the chemical-fortune scion John Eleuthere duPont died all alone, apparently of natural causes, in a western Pennsylvania prison cell where his frail and lifeless body was found at 6:55 a.m. yesterday. He was 72.

DuPont's millions were powerless against the psychological demons that caused his slide into insanity - which led him to reportedly declare himself the red-robed "Dalai Lama of the United States" and finally to gun down a gold-medal-winning Olympic wrestler for no apparent reason.

Declared "guilty but mentally ill" by a Delaware County jury, duPont spent the final 13 years of his life behind bars for killing wrestler David Schultz, a married father of two young children.

"He was certainly remorseful over the loss of Dave Schultz," said Taras Wochok, duPont's longtime attorney and friend. "From his own standpoint, I think, he stepped up and reconciled himself to the fact that he had to do the time for what he did."

Wochok said that he had visited duPont on Monday at a hospital in Somerset County, in western Pennsylvania, where he was being treated for severe emphysema and for chronic obstructive pulmonary disease. DuPont was returned to the nearby state correctional facility, where he died.

"He did not receive any special treatment," Wochok said of duPont's years behind bars. "In my view, he received less than the same treatment as other inmates because of who he was."

DuPont - who'd been sentenced to 13 to 30 years - lost an appeal of his 1997 conviction last year and had been denied parole twice. Wochok said that he couldn't attend the parole hearings but that he believed that duPont had been turned down for not accepting the police version of the events of Jan. 26, 1996, the day Schultz was murdered.

Life started much differently for the son of Delaware County businessman and thoroughbed-horse owner William duPont. His parents eventually divorced, and the young duPont remained close to his mother, Jean Liseter Austin duPont; in fact, some friends maintained that the son's unraveling seemed to begin after she died in 1988.

For much of his life, John duPont - who served in the Marines, and earned degrees from the Haverford School, the University of Miami and Villanova - was something of a dilettante, pursuing his interests in natural sciences and athletics.

He donated heavily toward Villanova's $15 million basketball arena - which was called the duPont Pavilion until his name was yanked after the murder - and spent two years as that school's wrestling coach amid reports of strange behavior.

Nevertheless, he built a world-class sports-training facility at Foxcatcher Farm, which attracted top amateur wrestlers and other prominent athletes. One was Schultz, who won a gold medal in freestyle wrestling at the 1984 Olympics in Los Angeles and who lived in a house on the property.

Meanwhile, there were reports that duPont was acting more erratically - that when he wasn't claiming to be the Dalai Lama, he said he was a CIA spy - that he abused alcohol or drugs and that he was obsessed with guns.

On Jan. 26, 1996, duPont was driving on the property when he pulled out a .44-caliber pistol and fatally shot Schultz three times in front of Schultz's wife, Nancy, and another witness. He holed up in his mansion for two days until police lured him outside by shutting off the heat.

Psychiatrists later testified that duPont was a paranoid schizophrenic. Ultimately, he was found competent to stand trial in Delaware County. The judge, Patricia Jenkins, told jurors that their finding - guilty of third-degree murder but mentally ill - meant that duPont was "both sick and bad."

Later, duPont reached a wrongful-death settlement for a reported $35 million with Nancy Schultz, who had moved with her children to California.

Patrick Meehan, the district attorney who prosecuted the case in Delaware County and who was elected to U.S. Congress last month, said yesterday that he has always "struggled" with why duPont did what he did, adding of duPont's time in prison: "In some way I wondered if his life was better-structured than it was before."

Wochok said yesterday that funeral arrangements for duPont had not been determined.