Tales of the Angel of Death, told over and over: they come from Auschwitz, from the jungles of South America, from CIA files, from fevered Nazi-struck imaginations, from hucksters of hellish relics. Somehow, they are all different, but all the same.

Take the woman in the jewelry store in Asuncio'n, Paraguay. She told an Israeli official about the day in 1965 when a customer asked about some merchandise. She came around the counter. She saw Josef Mengele. Two decades before, trim and elegant in his sleek black SS uniform, he had personally dispatched 400,000 other Jews to the ovens with a flick of his black-gloved wrist. But not her. She'd survived. And now he was browsing in her jewelry store, just one of 40,000 Germans living in Paraguay.

She could not speak, she would say later. She watched him leave and then she told her husband: "It was him. It was Mengele."

For 40 years, one of the monsters of history has wandered the globe untouched, a free man: the most notorious Nazi war criminal believed alive today, the Auschwitz doctor whose mass murders and grisly experiments evoke Evil Incarnate.

How can this be?

West Germany has had a warrant out for his arrest for 26 years and has added a $350,000 reward. Israeli Nazi hunters spirited Adolf Eichmann out of Argentina, but others have missed Mengele, they say, by minutes at a Paraguayan hotel, by little more at the Rome airport. CIA informants put him in Brazil, in Chile, in the drug trade or working as an auto mechanic. German prosecutors believe he may have been in Paraguay as late as 1982, if a jailed drug suspect can be believed: He is said to have been Mengele's roommate outside Asuncio'n, where they shared a passion for beekeeping.

What's more, the sightings began as soon as the Third Reich fell. American GIs say they saw him in an Army prison; a German professor claims he interviewed Mengele at a British prison camp in 1947. After that Mengele lived in his home town in Bavaria, where his family had made its fortune in the farm machinery business. His name arose at the Nuremberg war-crime trials, and he fled to Rome, where he is said to have gotten papers under the name of Gregorio Gregori.

In either 1949 or 1951, according to conflicting reports, he sailed from Italy to Argentina, where he lived under his own name in Buenos Aires, hawking heavy equipment for the family firm. Neighbors say he was "quiet, distinguished and courteous."

As Dr. Helmut Gregor, one of the dozen aliases he adopted over the years, he became an Argentine citizen in 1954 and performed abortions, says Nazi hunter Simon Wiesenthal. (At one point, he was "detained" by police when a patient died.) His first wife divorced him that year, and in 1958 he married his older brother's widow. They were divorced three years later, and she left for Switzerland and Italy. After the West German warrant was issued in 1959 he became a Paraguayan citizen; he is said to have attended his father's funeral in Germany that year.

He has lived his life. He has had friends, patients, family. Now bounty hunters, revenge seekers, glory hounds and die-hard believers in earthly justice descend on South America in such numbers that they have fostered a trade in relics of this saint of Hell -- photographs, an ID card, whatever souvenir of evil you want, except the man himself.

If alive, he would be 74 this month.

Now America wants him. Its top Nazi hunter, Neal Sher, a Justice Department lawyer who heads the Office of Special Investigations, flew to Europe last week to seek leads from German prosecutors and Nazi trackers like Wiesenthal, 76, who suspect Mengele is still in Paraguay, protected by President Alfredo Stroessner; but after all these years, they still don't really know.

On his SS application, he said he stood 5 feet 9, with brown hair and blue eyes. But others remember a shorter, darker-looking man in a country that worshipped blue-eyed blonds. Mengele's hang-up was that he "looked like a Gypsy," says Wiesenthal.

Indeed, he aimed to keep nature from future mistakes, drafting human guinea pigs for macabre experiments he believed might make Hitler's dream of an Aryan master race come true. As the SS doctor at Auschwitz, he dispatched nearly half a million to the gas chambers and killed thousands more with mad genetic quackery.

He was obsessed with twins: if German women could repopulate after the war with multiple births, military losses might be offset. He handpicked specimens as they came off the trains at Auschwitz-Birkenau deep inside Poland. In his black SS uniform, shiny stick in hand, he cut a striking figure to the bedraggled, frightened Jews, waving some to the left, to die, others to the right, to live.

"He looked gorgeous," recalls twin Eva Kor, 50, who sells real estate in Terre Haute, Ind. "But everyone was scared of him. He decided how long you lived."

One 12-year-old Jewish boy held a special fascination: Marc Berkowitz had blond hair, blue eyes and a twin sister, Francesca. SS officers on the lookout for lab rats perked up when their mother shouted, "Kill me, but not my twins!" Immediately, they were brought to Mengele, and the experiments began.

Berkowitz was ordered to disrobe and lie on a table. Fluid was drawn from his spine. "My whole body was burning, and the next thing I knew I was fighting back fainting," recalls the 53-year-old retired New York furniture salesman, physically disabled from his days at Auschwitz. He heard a whimper and reached out to comfort his sister. She lay on the next table.

At times, Mengele was almost gentle. He patted Berkowitz on the head as a nurse mopped his brow. Sometimes, he even apologized. "I'm sorry we have to do this, but the pain will go away," he said.

Yet if his "guinea pigs passed out, or fought back, he eliminated them," says Berkowitz, who watched bloody bundles carried out of the lab. Ever stoic, Berkowitz fought to detach himself from the pain, and did as he was told. Once, he stood on his head for hours without passing out. He was prodded, punctured and poked. He was dunked in a steel vat of freezing water while Mengele lab technicians monitored his plummeting body temperature.

At last, when he was pulled out alive, Mengele strutted about the lab in ecstasy. He liked Berkowitz's attitude. "You're the type of boy I've been looking for," he said. "You're setting an example. The other children are behaving themselves. We're getting good results."

Berkowitz just tried to obey, intent on living from "moment to moment, second to second." So pleased was the doctor with his star guinea pig that he made Berkowitz his "lauper," or errand boy. He taught him German songs, recited poetry. Mengele loved classical music, and Berkowitz hand-cranked his Victrola, shined his boots and harvested his brussels sprouts.

But Mengele's moods changed like the weather. One day, Berkowitz watched him shoot a boy, first in one knee, then in the other. The boy was weeping as Mengele grabbed him by the hair and gave the coup de gra ce with a bullet in the brain. His sin: he'd wandered away from his barracks.

"You know he had no business over there," said Mengele. He asked Berkowitz if he'd done "something wrong" in shooting the boy, but didn't wait for an answer. "You have to respect the laws of the place," he said.

All the time, the crematoriums were running. Twins who survived the experiments were spared, of course, treated like prize pet rabbits. But if one in a pair died, Mengele killed the other to compare autopsies.

In other experiments, he snatched babies from mothers and tried to change the color of their eyes and hair, then killed them by injection. "What's the difference if you make black eyes out of blue eyes?" he asked one mother, then tried it with her child. It died.

Witnesses have also told German prosecutors:

He offered candy to two sets of twin girls, then shot them in the neck, castrated or sterilized "about 100 male prisoners," routinely tossed babies into ovens alive and wired inmates with electrodes to test their threshold for electric shock.

To boost his labor force, he ordered pregnant women onto their backs, then stomped them until they aborted. Once, he promised a special milk porridge for all expectant mothers who signed up, then gassed them all. He also gassed a barracks that included some of his former professors, all Jews.

"We called him the 'death doctor,' " says survivor Ernest Michel, 61, of New York City, who once escorted eight Jewish women to Mengele's lab as an orderly. When he hauled them away, two were dead, two were in a coma, another had to be disconnected from an electroshock machine.

Spared for his elegant penmanship, Michel was ordered to rewrite medical history. "Heart attack," he wrote day after day to cover up the true cause of death. "Our biggest fear was that no one would be left alive to tell what really happened," he says.

As one of Mengele's pets, Berkowitz was there in 1944 when his keeper exploded over a report of lice among the Gypsies. "I'm sick and tired of these filthy, diseased pigs," Mengele ranted. "I've been trying to keep this camp clean, and I'm fighting a losing battle!"

His solution: send the whole barracks to the gas chambers. And 700 Gypsies were marched off to be "disinfected" forever. One German officer nodded at Berkowitz, a witness to his rage. Said Mengele, "Don't worry, he's one of us. If we had more boys like him, we would have won the war."

Mengele liked to test Berkowitz, probing for the secret of his endurance. Once, he ordered Berkowitz to swim with the SS men who nearly drowned him for sport. To retest his courage, it was back to the pool.

When his mother's barracks was marched off to the gas chamber, Mengele conjured an errand so Berkowitz could take a last walk with Helen Berkowitz. For Mengele, it was just another experiment, the Angel of Death testing the faith of a Jew.

"So," asked Mengele later, "do you still believe in God?"

"I've lost almost everything," replied Berkowitz, "but one thing I have not lost is God. You can take everything from me, but you cannot take my God."

Mengele reached for his revolver. It was holstered in black leather, hanging over a chair. He unsnapped one button. He unsnapped the other. He stared long and hard at his gofer.

"You gave the right answer," he said. He nodded at his boots. "I want a good shine today. I have very important things to tend to."

Berkowitz walked outside. Smoke was belching thick and black. He was thinking, "I'm only 12, but I'd better say Kaddish (the prayer for the dead) for my mother. I don't know if I'll be around to say it tomorrow."

On Christmas Eve 1944, with the Russians advancing on the eastern front, Mengele found Berkowitz in the washroom. A light snow was falling. Pausing at the door, flanked by two SS guards, he wished him well. Mengele seemed almost wistful. "Adieu," he said. And that was the last time Berkowitz saw him.

Everyone has an answer, a rumor, a theory, a cold lead, an excuse.

"I've barely missed him five times," says Wiesenthal. He has bagged 1,100 war criminals in his lifetime without ever getting as close to Mengele as the jeweler's wife.

Christmas 1963. Wiesenthal got tipped off in a letter: Mengele, Hotel American, Milan. He flew there with a German prosecutor. Said the manager, "Yesterday, he left." In Torremolinos, Spain, he missed him by two days; at the Rome airport, by mere hours.

Later, a group of Auschwitz avengers called the "Committee of 12" tracked him to the Hotel Tyrol near the thriving German colony of Hohenau in eastern Paraguay. They planned to spirit him to Frankfurt to stand trial. His alias that time: Dr. Fritz Fischer. They burst into room 26, but he was gone. Minutes before, Herr Fischer got a phone call, said the manager, raced down the stairs with his pajamas on under his suit, and vanished in the night.

Intelligence tips put Mengele in Chile 18 months ago; in Paraguay's German-speaking Mennonite villages on the Bolivian border as recently as last year; in Uruguay six months ago.

South American governments, rubbed raw by complaints that they're sheltering the fled legions of the Nazis, deny it all.

Says the Chilean Embassy press officer: "We had one Nazi war criminal, and that was plenty." That would have been the late Walter Rauff, the SS general who conceived and operated mobile gas chambers used to exterminate Jews. He recently died in his sleep after running a fishing boat for years, under his own name, out of Puerto Provenir. Chile's supreme court denied his extradition request on a technicality. Another extradition request was denied in 1959 by Argentina, on grounds that it was written in German, not Spanish. And not till 1970 did Paraguay concede Mengele had been naturalized years before.

"The last photograph is 1963 in Asuncio'n," says Wiesenthal by phone from Vienna. "We don't know his [new] alias."

What of rumors he may have undergone plastic surgery? Wiesenthal doubts it; no Nazi war criminal he caught ever went under the knife. What about the report of postcards sent to friends from Portugal? Does Wiesenthal say this is a Nazi disinformation trick to blur the trail?

Or CIA files portraying Mengele as a cocaine warlord, dealing under the name Dr. Henrique Wollman? "A stupid story," Wiesenthal scoffs. "He doesn't need the money."

It would certainly seem that way, if he can rely on rich Nazi friends and the family conglomerate, Karl Mengele & Sons, with offices in Paraguay, Argentina and the United States.

A $1 million bounty was offered last week by unnamed donors in Los Angeles after lesser amounts did no good.

He remains at bay, a fugitive with all the glamor of an emissary from hell, merely yapped at by the hounds of justice, and mythologized by Hollywood in two movies, "Marathon Man" and "The Boys From Brazil."

Mengele was born March 16, 1911, in Guenzburg, Germany, the third son of a wealthy farm machinery manufacturer. At 24, he joined Hitler's "Brown Shirts," the Nazi Party three years later.

He studied anthropology and zoology in Munich, hatching a fascination for genetics, which was further fueled at the Institute for Genetic Purification in Frankfurt. In 1938, he graduated from medical school, married Irene Maria Schoenbein, joined the Waffen SS and became the Auschwitz camp physician.

Their son Rolf was born at Auschwitz in 1944.

Like other Nazis in the early days after the war, he made little effort to hide his identity.

But at least two U.S. Army veterans say they believe he was in U.S. custody at one time. A retired California aerospace engineer, Walter Kempthorne, says soldiers put a red-faced prisoner through calesthenics around July 10, 1945.

"This here's the bastard who sterilized 3,000 women at Auschwitz," said one, as a man fitting Mengele's description huffed and puffed. Kempthorne was 19, a private at the Idar-Oberstein detention camp in occupied Germany, where Nazis were interrogated after the war.

Guards sometimes trotted them outside for fun and games, including a charade called "Luftwaffe": Prisoners were ordered to run around in circles "spitting like a plane," says Richard Schwarz, 59, a retired government labor lawyer in Washington, D.C. As a young private, he put a Nazi he now believes was Mengele through the drill, "pats on the fanny" and all.

"Presumably, it was Mengele," recalls Schwarz, who never heard the man's name, but has war correspondence indicating he wrote friends about just such a doctor. And the Simon Wiesenthal Center in Los Angeles, which hunts data on Nazi war criminals and supports Holocaust studies, turned up the two soldiers, along with a U.S. Army dispatch from an intelligence officer who refers to an account of Mengele's arrest in 1947.

"We're searching our records of that camp," says Lt. Col. Craig McNab, an Army spokesman. "You've got to understand, Mengele wasn't on top of anyone's list back then. In 1945, he was a doctor way off in the wilds of Poland."

And by the 1950s, he was long gone. In South America, the chase began, a slow and frustrating pursuit. Diplomatic channels yielded nothing. Everything grew vague.

Isser Harel, Israel's secret service chief who pulled off the daring snatch of Eichmann from Buenos Aires in 1960, eyed Mengele, too, but didn't want to risk losing Eichmann, he once wrote. Afterwards, Israeli agents tracked down his house in a middle-class suburb of Buenos Aires, but he was gone. They traced him to Paraguay. There, it was believed, he was protected by President Alfredo Stroessner, the right-wing strong man who took power in 1954, son of an immigrant German cavalry officer. It was easy to hide in a remote California-size country with only two million people and a gossipy capital where word travels fast when outsiders come sniffing around.

There was also plenty of camouflage from German colonies to the east, where lush, rolling hills between the Paraguay and Parana rivers lured refugees of the Third Reich to drive Mengele tractors around some of the world's most fertile sub-tropical farmland.

It was there Mengele was sighted in the '60s, from Pedro Juan Caballero, a coffee-growing town to the north, to Hohenau, a farming village to the south. Israeli agents staked out a hideout in a heavily fortified farmhouse nearby in the early '60s, but ruled out a commando raid. There was no airport nearby to pull off an Entebbe, and Israel couldn't afford any diplomatic casualties: the Eichmann affair had ended their honeymoon.

Agents kept up their search in Asuncio'n and the interior, then lost Mengele across the border in Brazil, according to heavily edited CIA files released last week. Accounts also surfaced of assorted avengers on the loose, and someone apparently mistook a man for Mengele. He was found beaten to death, but it turned out to be an ex-Nazi soldier.

Diplomacy offered another route for frustration. When West Germany's envoy protested in 1965 that Mengele's citizenship was invalid, Stroessner is said to have exploded in rage. "Once a Paraguayan, always a Paraguayan!" he shouted, pounding the table.

Especially when the citizenship papers are signed by old Stroessner friends like Alejandro von Eckstein, a Russian e'migre' who fought alongside Stroessner in the Chaco War with Bolivia, and who still advises Paraguayan intelligence services.

At the American Embassy at Asuncio'n, there were frequent rumors of Martin Bormann alive and well, but never Mengele, recalls A. Dane Bowen, political officer until 1964. Besides: "Hunting Nazi war criminals wasn't our big preoccupation."

In those days, Mengele lived openly, sunning at a villa a half-mile from the embassy and scouting for land in Alta Parana, just across the Argentine border, reportedly working as an auto mechanic northeast of Asuncio'n near the Brazilian border. "Recurring rumors" said that Mengele was at a "well-guarded ranch, either near Encarnacio'n, in eastern Paraguay, or in Chaco, and that he is protected by Stroessner," said a 1972 CIA report.

Veterans of the Asuncio'n diplomatic corps say Mengele socialized with late Nazi Luftwaffe ace Hans Ulrich-Rudel, reputed mastermind of Odessa, the secret underground that resettled fleeing Nazis in South America. Rudel was a fixture at diplomatic receptions, a favorite of Stroessner, and a representative for German firms.

His dealings also included substantial payments to Stroessner's son, says Paris-based Nazi hunter Beate Klarsfeld, who, along with her husband, tracked Nazi war criminal Klaus Altman Barbie to Bolivia, where he lived openly as a government security consultant before his extradition to France. She claims Rudel's financial documents, in her files, detail the deals.

"I bumped into Rudel all over the place," says Benjamin Weiser Varone, 71, the former Israeli ambassador who made it a habit to befriend those like the jeweler's wife who had seen Mengele. He met Mengele's lawyer, dutifully filing such reports to Tel Aviv. He got no reply.

"Israel doesn't expect its ambassadors to be Nazi hunters," he says. But whenever Nazi hunters back home raised a fuss, Paraguayan officials called Varone on the carpet. "They would call me to express the displeasure of their president," says the retired diplomat turned writer, who lives in Brookline, Mass. "But they never denied he was there."

Naturally, Varone was a magnet for mercenaries and crackpots chasing the doctor. His standard line: "Go across the street. The Germans have a warrant for his arrest." His job was to keep Paraguay's crucial U.N. Security Council vote in Israel's corner. He charmed, he cajoled, he got it, even as Mengele was seen around town.

Later, in 1978, the U.S. Embassy heard he frequented the Caballo Blanco, or White Horse, a favorite German restaurant downtown. And a BBC crew with a hidden mike captured a Nazi boasting of playing cards with the doctor.

"Mengele? Oh, yes, he's around, but we don't know quite where. He comes and goes," officials would reply whenever Ambassador Robert White brought it up.

So, why wasn't he arrested -- or something? "Because he wasn't wanted all that much," says White, who filed his Mengele tales with the State Department and got no reply. "We did report on it, but there was never much interest expressed by Washington in any way."

Still, such accounts irritated officials in the remote haven for right-wing refugees. "Bob, how can we polish up our image?" he was often asked.

"A good place to start would be to cancel Mengele's citizenship," he replied. Then, one day, out of the blue, the foreign minister said, "Bob, that's a wonderful idea. I'll bring it up with the president." And, in 1979, Mengele was stripped of his citizenship for being "out of the country for more than two years."

"We knew he was in Paraguay, but it's not something we pursued," says Alan Ryan, the top Nazi hunter for the Justice Department until 1983. There was no jurisdiction, and Ryan was too busy chasing Nazi war criminals hiding in America to go "smoke him out of the jungle."

These tales, of course, contradict Paraguay's official shrug that his whereabouts has mystified them since 1962, when Germany's first extradition request arrived. But if a hideout can be found, they promise to dispatch a posse. "We have made afull investigation and found no trace of Mengele in Paraguay," says the embassy press attache. "We believe he is not there anymore."

Horrors like the Holocaust make Everyman a philosopher. Questions beget more questions. If Mengele is never caught, does that mean you can do unspeakable things in this life and escape justice? Or if he is put on trial, will that mean good finally triumphed over evil?

On Jan. 27, 1945, Berkowitz and his sister were liberated by the Russians, after surviving a death march in the freezing cold. And three years later, after stints in refugee camps, they wound up in America, sole survivors of a family of nine.

Berkowitz washed dishes in New York, sold furniture, shrugged off the pain of a crumbling spine and fought to understand. With Eva Kor, he started a support group for Auschwitz twins called Candles. So far, about 120 have come forward, 20 from the States. Many testified at a mock trial for Mengele in Jerusalem last month.

If Mengele is ever arrested, Berkowitz wants to ask him some questions. "I would like to ask him exactly what he did to his guinea pigs, so we can get medical help," he says. "We are like a puzzle. We have to be put back together piece by piece."

Ambivalent about revenge, he would prefer a trial. He doesn't hate Mengele. And he reflects that he is still his errand boy: "You see, he never dismissed me."

Says Wiesenthal: "Look, the life of Mengele is without importance. After so many years, criminals turn into witnesses. How can you punish somebody for the deaths of 400,000 people? If he is caught and gets life, he'll probably serve only a few years before he dies. That will end up to be a few seconds per victim.

But if Mengele is sent to the gallows, "the survivors should do it," says Berkowitz.

Now Mengele is hot, everyone's favorite villain. It's only taken 40 years. In South America, there are those who can look on it as a trend, not unlike other trends, a sort of nostalgia craze.

"There are people out there willing to sell you Bormann's bones and Mengele's hacienda," says New York lawyer Gerald Posner, whose research forays draw Nazi brokers like flies. "The minute they hear an American is hunting Nazis, their ears perk up and their wallets get itchy."

He's spurned diaries, rings and memorabilia. How about Mengele's original fingerprint card? asked a Brazilian cop. Only $500. Or recent photos, whispered an ex-Nazi officer over mint tea at the Hotel Mansour in Casablanca -- after plastic surgery. A mere five grand. Or, maybe you like Mengele's SS ring, very cheap: $1,000, said the Argentine lawyer.

The flea market sells such rings by the trayful, swastika and all, $3 apiece