(FORTUNE Magazine) - One of the the jaw-dropping moments in the trial of former CEOs Ken Lay and Jeff Skilling came when former CFO Andy Fastow discussed the road show that Enron executives set up to reassure skittish investors right after Skilling's abrupt resignation in August 2001.

Following a dinner in New York City, the Enron team flew on to Boston -- everyone, that is, except Greg Whalley, the company's soon-to-be president, who had announced he was returning to Houston. "Why are you leaving?" Fastow said he asked Whalley. "If I met with investors, if I came to Boston, I'd have to lie too much," Whalley responded, according to Fastow.

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There have to be plenty more anecdotes where that came from, once Whalley takes the stand -- or there would be, if he ever does. But he almost certainly won't. Nor will some other highly colorful players in the Enron saga show their faces inside the courtroom.

Where, for example, is Lou Pai, the enigmatic Jeff Skilling confidant with a passion for strip clubs who netted $200 million from Enron stock -- more even than Ken Lay? Where is Rebecca Mark, the hard-charging glamour girl who planted troubled Enron energy and water projects around the globe?

The reasons we probably won't be seeing these people as witnesses -- let alone as criminal defendants -- range from legal strategy to simple luck. After all, bad business judgment isn't a crime -- or maybe someone else presented a better prosecution target. Or someone else is a more compelling witness. (The government has ruthlessly narrowed its case, never calling two witnesses when one might do.)

Some of the absent executives might offer benign accounts of what really happened, but they aren't likely to appear for the defense either -- most would likely take the Fifth Amendment unless the government grants them immunity from prosecution, which isn't going to happen.

Are these ghosts of Enron the luckiest people in Houston? As long as they stay in the shadows they are. As the attorney for one former Enron executive put it: "He ain't getting within a thousand miles of the courtroom."

Whalley, now 44, was long one of the central characters in the Enron drama, although he only burst into public view during the company's final months. A former Army tank commander, he joined Enron in the early 1990s and soon became a trading-floor star, eventually running the whole trading operation. The traders idolized Whalley. They saw him not only as honest, but as someone who could right the wrongs at Enron.

But in court testimony a different picture has emerged--of a guy who tried to help cover up problems. For instance, both Fastow and former Enron treasurer Ben Glisan testified that at a meeting of Enron's top executives in early September 2001, the company was coming roughly $500 million short of an earnings target.

"Don't worry about it," Whalley responded, according to Fastow's testimony. "I'll cover it off with the reserves." Glisan said Whalley knew it was wrong to be using reserves as an earnings-management cookie jar. "Not taking income when you should is just as wrong as taking income when you shouldn't," Whalley remarked, according to Glisan.

In Enron's glory years, Whalley's close friend and rival was David Delainey, who in 2003 pled guilty to insider trading and gave some of the government's most powerful testimony against Lay and Skilling. Delainey recalled objecting to a plan to hide hundreds of millions of dollars in losses, at a meeting of executives. He said that Whalley responded by shoving his chair back from the table, seemingly in exasperation.

On cross-examination, Skilling attorney Daniel Petrocelli asked: "So I guess what you're saying is that all these people were in on this massive fraud, right?"

"Unfortunately, yes," responded Delainey. He also testified that in October 2001 he and Whalley were having a drink when the topic of the buried losses came up. "Yeah, that was a little dirty," Delainey says Whalley remarked.

So where's Whalley? The government has opted not to call him. He's been on the defense witness list, but he would almost certainly take the Fifth if called. He now works in Houston for another ex-Enron hotshot, John Arnold, who started a hedge fund after Enron's collapse.

Arnold's fund, started with $8 million of his own money, has performed spectacularly and now has some $1.5 billion in assets. It's safe to assume Whalley has made millions too.

One theme of the prosecution has been the abymsal state of both Enron's international assets and its water business, Azurix. For instance, Fastow testified that in July 2001 Whalley said that all the heads of the international business should be fired because they had done billions upon billions of bad deals. According to Fastow, Skilling "didn't disagree" that Enron's international businesses "were generally a disaster."

Prosecutors walked both Glisan and Fastow through an analysis showing that, by Skilling's own estimation, the international assets and Azurix were overvalued on Enron's books by $4.3 billion. This massive gap, Fastow testified, would have been "devastating information to disclose to the public."

All of which raises the question: What's happened to the architect of these businesses -- Rebecca Mark, whom FORTUNE named one of the 50 Most Powerful Women in Business in 1998 and 1999? Her name has hardly been uttered during the trial. Yet it is Mark, along with Fastow, whom Skilling once blamed for Enron's destruction. "Rebecca poured gasoline all over the balance sheet, and Andy lit the fuse," he said privately.

Prosecutors never viewed Mark, whom Skilling finally pushed out in August of 2000, as a target. She may not have been the best businesswoman, but that's not a crime, and there's no evidence she tried to cover anything up. Although she has been on the defense witness list, it's not clear they'll call her even if she is willing to testify, since she left Enron too early to know much about the government's specific in-court allegations against the former CEOs.

Mark was also lucky. She sold more than $80 million worth of Enron stock near its high. (In early 2005 she agreed to pay $5.2 million of that to settle her share of a lawsuit brought by former Enron stockholders.)

She has remarried and now goes by the name Rebecca Mark-Jusbasche. At age 51, she manages a family cattle ranch in northern New Mexico, and is also a director of a company that sells water-purification systems to developing countries.

If ever there were a juicy government target, Lou Lung Pai would seem to be it. He was close to Skilling, he ran the controversial Enron Energy Services division, and he netted a mind-blowing fortune from Enron stock.

He also had a legendary fondness for strippers, and was a frequent habitue of a Houston topless club called Rick's Cabaret. It is there that Pai, who was married and had two children, met Melanie Fewell, with whom he began an affair that lasted for years and produced an out-of-wedlock daughter.

In fact, it is this relationship that prompted his 2000 divorce, whose settlement required the highly fortuitous unloading of most of his Enron stock before the price began to tumble. This scenario has insulated Pai from charges of insider trading. "He's the only guy who's ever been lucky to get divorced," says Deborah Jeffrey of Zuckerman Spaeder, Pai's Washington attorney.

Pai has kept a low profile ever since leaving Enron. Although there has been extensive testimony about EES's problems -- Delainey, who replaced Pai in early 2001, called it a "basket case" -- the allegations of fraud at EES primarily involve later events, such as the transfer of EES losses into the wholesale division and public assurances about the business's success.

Pai has been on the defense's witness list, but don't expect to see him on the stand; he took the Fifth in the Enron class-action civil suit. "Lou would prefer not to be a witness," says Jeffrey. "That's what any lawyer would advise. You won't see him hanging around the courthouse."

Pai, 59, continues to live in Houston with the ex-stripper -- now his wife -- and is considering launching a small energy business, according to his lawyer. "The worst people could say of him was that he didn't manage EES well, and I'm not sure that's true. But it sure isn't fraud," says Jeffrey. "Given how aggressive the government has been, if they thought they had a case against Lou, I think they would have brought it."

Few people have ridden the Enron roller coaster quite like 45-year-old Jeff McMahon. Arriving at Enron in 1994, he preceded one key government witness (Glisan) in the role of corporate treasurer, and in October 2001 succeeded another (Fastow) in the role of CFO. But unlike Glisan and Fastow, McMahon has avoided prosecution, despite his significant role in one of Enron's most infamous deals: the Nigerian barge case.

The deal went like this: Merrill Lynch agreed to buy three Nigerian power barges from Enron near the end of a quarter, after receiving a verbal guarantee that the barges would be repurchased six months later at a guaranteed profit. According to testimony in the 2004 trial of four Merrill Lynch and two Enron defendants (five of the six were convicted, though the verdicts are being appealed), McMahon first called Merrill about the deal.

He has insisted he did nothing wrong, and he has not been charged. But he also didn't testify, after threatening to plead the Fifth. And though he has been on the defense witness list for Skilling and Lay's trial, it seems highly improbable he will take the stand in Houston.

Meanwhile, McMahon has gone about his life, landing in 2004 as president of a Houston company called Zilkha Biomass Energy, a renewable-energy outfit. If only all of Enron's former executives could recycle their reputations.

REPORTER ASSOCIATE Joan L. Levinstein

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