As Mey Mann remembers him, Saloth Sar was "a joyful, pleasant boy who loved life," a friendly and warm-hearted "bon vivant" with little interest in politics.

That was in 1949, when Mey Mann, Saloth Sar and 20-odd other Cambodian students sailed to France to continue their educations.

Over the next 14 years, as both men became fellow communists and high school teachers in Phnom Penh, Mey Mann said, "I didn't see any cruelty in him. . . . He didn't seem mean at all."

Now 75, with thinning white hair, Mey Mann is hard-pressed to explain what happened to his friend, who is better known to the world by the "revolutionary name" he later adopted: Pol Pot. Certainly, their early friendship and political affiliation did not save Mey Mann from being forcibly evacuated from the capital when his former classmate came to power, nor from having three children and a son-in-law taken away and killed during the brutal Khmer Rouge regime that Pol Pot presided over from April 1975 to January 1979.

How did this outwardly cheerful bon vivant become one of the world's most vilified men, the engineer of a holocaust that claimed the lives of more than 1 million Cambodians in less than four years? And how, after being driven from power, did he survive for so long as the murky master, unseen by outsiders for 17 years, behind what was arguably once the deadliest and most feared guerrilla army in the world?

What seems clear at this point is that Pol Pot's long run is over. The reclusive leader known during his pitiless regime as "Brother Number One" launched one purge too many, triggering a revolt by Khmer Rouge remnants at his last remaining stronghold in northern Cambodia.

Now, according to a Cambodian general who reports having seen him twice in the past 2 1/2 weeks and to military intelligence reports from Thailand, Pol Pot is under guard north of the Khmer Rouge village of Anlong Veng, held by fighters loyal to a feared, one-legged commander and longtime Pol Pot stalwart code-named Ta Mok.

In a twist of history, he may now be sharing the same uncertainty that gripped countless victims of his rule, not knowing whether he is also destined to share their fate.

The infighting reflects splits that first opened decades ago and fueled purges that devoured thousands of Khmer Rouge cadres, historians say. The Khmer Rouge leadership managed to stay united after invading Vietnamese forces drove the group from power in 1979, but the rifts reappeared over a 1991 U.N.-sponsored peace agreement, widened during elections two years later and eventually led to the latest breakup.

Aging, infirm and publicly accused by his former comrades of "treason," Pol Pot, who is believed to be at least 69, effectively has been reduced to a bargaining chip in negotiations between the Khmer Rouge remnants and a faction of the Cambodian government under Prince Norodom Ranariddh, one of the country's two rival but jointly ruling prime ministers.

The Khmer Rouge appear to be trying to disentangle themselves from Pol Pot and his legacy with the aim of revitalizing their more than 30-year-old movement, launching a new political party and promoting a new generation of leaders, Cambodian and Western analysts say.

Statements broadcast on their clandestine radio station suggest that while the Khmer Rouge want to be rid of Pol Pot, they have not quite decided what to do with him. The Cambodian government wants him turned over for trial before a proposed international tribunal, but the prospects for that appear to be fading, in part because Ranariddh's coalition partners adamantly oppose any concessions to Pol Pot's captors and any resulting political or military advantage for the prince. The alternative may be for the former dictator to live out his remaining days under arrest in a house close to the Thai border, where he reportedly has been under the care of a Khmer Rouge doctor.

Interviews with his contemporaries, defectors' accounts collected by researchers and documents that have filtered out of Khmer Rouge zones show Pol Pot as an unprepossessing man at first glance, but one with a rare ability to mesmerize listeners, motivate followers and patch up differences between competing factions. He has continued to show an unwavering hatred of neighboring Vietnam, Cambodia's traditional enemy, but the paranoia that he displayed in the past about perceived enemies within the movement's ranks apparently abated in recent years. By all appearances, the man renowned as perhaps the bloodiest tyrant of the late 20th century seemed to have mellowed.

For the past four years, Pol Pot has lived north of Anlong Veng in a modest house close to the Thai border with his second wife, a porter in a female Khmer Rouge unit, whom he married in 1987. They reportedly have two children, the eldest a 9-year-old girl. Defectors have described him as fond of gardening and affectionate with his daughter. He is reputedly a teetotaler, and one former Khmer Rouge officer has said he is a vegetarian.

Protecting him for years has been a personal bodyguard unit of about 70 ethnic Khmer Loe hill tribesmen from northeastern Cambodia.

Although Pol Pot long ago gave up all his titles, he had remained the real power behind the Khmer Rouge and regularly conducted seminars for military commanders. With a calm demeanor, he spoke simply and clearly, without notes, rarely raising his voice, often lightening his remarks with humor, and occasionally reducing his listeners to tears.

According to Mey Mann, these were skills he developed as a teacher in Phnom Penh in the late 1950s and early '60s, when he taught history, geography and French literature at a private school. Speaking in French, the language of instruction then, he would season his lessons with verses of French poetry recited from memory. By all accounts, he was popular with his students.

"He had the gift of making himself understood by young people," said Mey Mann, who taught at another school.

Mey Mann and Western historians agree that the man who became Pol Pot showed little interest in politics before sailing to France to study radio-electricity in Paris. There, he was drawn to Marxism and, after neglecting his studies and losing his scholarship, he joined France's Stalinist Communist Party and returned to Cambodia in 1953.

Three years later, he married Khieu Ponnary, a dour fellow teacher and communist eight years his senior. Her sister had earlier married Ieng Sary, an active Marxist who had met Pol Pot in Paris and later became the Khmer Rouge foreign minister.

One of Ponnary's former students here recalled her as a tightly disciplined teacher who was highly critical of Buddhist monks. She became a leading Khmer Rouge activist, but went insane during the group's horrific rule and was institutionalized in Beijing for a time during the 1980s, according to Mey Mann and other sources. She now reportedly lives in western Cambodia in an area controlled by a Khmer Rouge breakaway faction.

Pol Pot, still known then by his given name of Saloth Sar, rose to the leadership of the underground communist movement in 1962, then fled the capital the following year to build a guerrilla force in the countryside when the government of Prince Norodom Sihanouk cracked down on those he dubbed les Khmers Rouges, or Red Khmers. Mey Mann said that was the last he saw of his friend, but not the last he felt of his influence.

Pol Pot set up camp in Cambodia's northeastern jungles, protected by a force of Vietnamese communist guerrillas. A pivotal event during this period was a trip he made to China in 1966 at the onset of Mao Zedong's Cultural Revolution.

Among the measures that apparently impressed him during this tumultuous time were the partial evacuations of Chinese cities, purges of "class enemies" and pursuit of the Maoist economic program known as the Great Leap Forward, according to historian David P. Chandler.

But the major break for the Khmer Rouge came in 1970 when Sihanouk was deposed by Lon Nol, a general who enjoyed U.S. backing. The prince threw in his lot with the Khmer Rouge, whose forces then burgeoned from about 5,000 guerrillas to more than 70,000. While using Sihanouk as a figurehead, Pol Pot also managed to distance his movement from the Vietnamese and, by 1975, to defeat Lon Nol.

To his followers, he was a military and political wizard, said Steve Heder, a leading expert on the Khmer Rouge. "The victory of 1975 was a feat of genius," Heder said. "He outfought and outfoxed Sihanouk, Lon Nol, the Americans and the Vietnamese at the same time. Many believed it couldn't be done."

Pol Pot then began implementing a strategy of rapid social transformation aimed at engineering his own "great leap forward" and constructing a pure communist state starting from a Cambodian "Year Zero." According to Heder, the policy sprang from a view that Cambodia was "behind" other countries and could catch up only by creating an "advanced proletariat."

What followed, however, was an extreme expression, based on a half-baked melange of Marxism and Maoism concocted during years of isolation in Cambodia's jungles, of the end justifying the means. It began with the emptying of cities, viewed as hotbeds of capitalism, and the systematic slaughter of former Lon Nol soldiers and government officials.

No one was spared. Among the 2 million people forced to trek out of the refugee-swollen capital to work the land in distant provinces were two of Pol Pot's brothers and a sister-in-law. Like thousands of others, Pol Pot's older brother, Saloth Chhay, died on the way.

Mey Mann and his family, including his wife and nine children, also had to leave. They fashioned a crude cart for his 87-year-old father, who could not walk, and headed for Prey Veng Province, taking a month to travel about 50 miles, he recalled. Soon, his 15-year-old son was taken away without explanation and Mey Mann never saw him again. Later, after being forced to move to western Cambodia, he lost two more sons, aged 13 and 14, and a son-in-law.

In pursuit of their dreams of a communist Utopia, the Khmer Rouge abolished money, commerce, religion and traditional education. They suppressed family relationships, individualism, intellectuals and ethnic groups, slaughtered anyone who showed recalcitrance and enforced unquestioning obedience to "Angka," the organization.

Thousands were beaten to death, then dumped in mass graves in the regime's "killing fields." Many more succumbed to starvation, disease and overwork. Out of a population of about 8 million, demographers and researchers estimate, at least 1 million, and possibly as many as 1.7 million, died.

But as the killing intensified, the revolution increasingly turned on itself, targeting "enemies" whom Pol Pot perceived to be multiplying like germs, creating what he called a "sickness in the party."

By late 1978, numerous top officials, particularly those suspected of allegiance to Vietnam, had been executed after being tortured at an infamous former school known as Tuol Sleng. Among those targeted for a purge, according to Heder's research, were Son Sen, Pol Pot's defense minister and the official in charge of Tuol Sleng, and his wife, Yun Yat, the minister of propaganda.

They were saved, in effect, by the Vietnamese army, which responded to a series of border skirmishes by invading in December 1978. Within two weeks, the Vietnamese ousted the Khmer Rouge, including Pol Pot and Son Sen, from Phnom Penh and installed a communist regime led by Khmer Rouge defectors obedient to Hanoi. But while Hanoi insisted it had done the world a favor, China, the United States, Thailand and most of Southeast Asia reacted with alarm, fearing Vietnamese expansion. Thailand gave the Khmer Rouge sanctuary, and China began rearming them to wage a guerrilla war against the occupying Vietnamese.

Driven to the Thai border with thousands of other refugees, Mey Mann ended up spending the next 13 years in a Khmer Rouge camp with what remained of his family.

As the excesses of his rule became known, Pol Pot receded into the background, gradually renouncing all political and military titles. But he reportedly continued, secretly, to call the shots from his remote bases.

Pushed to the fore was Khieu Samphan, an austere French-educated former legislator who emerged as the figurehead president of Pol Pot's "Democratic Kampuchea" regime.

After the Vietnamese withdrew in 1989, the Khmer Rouge signed a U.N.-sponsored peace plan two years later that provided for the disarming of all factions and the holding of free elections in 1993. The guerrillas eventually reneged, and the elections went ahead without them as Cambodians overwhelmingly defied Khmer Rouge threats to cast their ballots.

To a large extent, it was the peace plan that began the unraveling of the Khmer Rouge, reopening an old split between proponents of a political option and those who favored fighting on militarily to regain power. The former included Ieng Sary, while the latter were headed by Ta Mok. Pol Pot sided with Ta Mok.

But the rank and file's enthusiasm for further warfare waned after the elections were won by a royalist party formerly allied with the Khmer Rouge. A stream of defections began to erode the organization. In mid-1993, according to researcher David Ashley, who has interviewed numerous defectors, Pol Pot moved to the Anlong Veng stronghold of Ta Mok, a former Buddhist pagoda teacher.

Efforts from there to rev up the military struggle, crack down on free enterprise and resume class warfare further alienated Khmer Rouge followers, leading to a major split last year. Ieng Sary broke with his brother-in-law, taking with him key commanders and several thousand troops. The government gave him amnesty.

The tensions this created came to a head last month in Anlong Veng after secret negotiations with the government faction of Sihanouk's son, Prince Ranariddh. The prince has been locked in a power struggle with Second Prime Minister Hun Sen, and both have been competing for the allegiance of Khmer Rouge defectors to bolster their forces for elections next year.

Down to about 2,500 fighters, the remaining Khmer Rouge leaders opted to pursue a political struggle behind Khieu Samphan and a new party, analysts believe. But a deal to make the party palatable by sending Pol Pot and other senior leaders into exile apparently foundered when no country would take them, and they turned on one other. Pol Pot ordered the massacre of Son Sen and his family. Ta Mok's forces responded by capturing Pol Pot and bringing him to Anlong Veng. For many Cambodians, these events have revived traumatic memories of Pol Pot's rule. His former friend Mey Mann, for his part, cannot help thinking of his three dead sons.

"I don't understand why they passed before me," he said sadly, his face etched with pain, "and why I am still living." CAPTION: Pol Pot, shown at a 1979 jungle news conference, is blamed for the death of more than 1 million Cambodians. He reportedly is now a prisoner of rival forces.