Die Karamadenwerk, Odessa, Der Spinner. For years, reports of a secret Nazi underground that shelters and supports former Gestapo and SS officers now hiding in South America have been commonplace, fed by best-selling novels and movies such as "The Boys From Brazil," "Marathon Man" and "The Odessa File."

Hard evidence of course, has been more difficult to come by. But information emerging after the capture in South America of prominent Nazis such as Adolf Eichmann (Argentina, 1960) and Franz Paul Stangl (Brazil, 1967) has led investigators such as Simon Weisenthal to conclude that such a network does exist - and that it harbors some 8,000 to 10,000 Nazi fugitives.

The last time Alfred Winkelmann and his "friends of the 20th of April" got together at the Hotel Tyll here, their "celebration" of Adolf Hitler's [WORD ILLEGIBLE] triggered an investigation that led to the arrest of an alleged Nazi war criminal: Gustav Franz Wagner, "the human beast" accused of supervising the extermination of over a million people as second-in-command at the notorious Treblinka and Sobibor concentration camps.

When police arrived on April 23 they found they had stumbled on to an international congress of Nazi and neo-Nazi organizations bringing together five groups from four nations.

The participants were questioned, photographed and released, and their private stocks of Nazi literature and emblems seized. One month, later, Wagner, who had been identified in Vienna by Nazi-hunter Simon Weisenthal - mistakenly, as it turned out - as one of the participants at the Italiaia conference, was arrested in Sao Paulo after 28 years at liberty in BraziL.

That was "not the first time Nazis have met in Brazil," said Benno Milnitzky, president of the Jewish Federation of Brazil, they have met here before, and they will meet here again."

This weekend, some of the same "friends" were again reunited at the hotel on the outskirts of this quiet mountain resort town 110 miles northwest of Rio de Janeiro. The occasion: July 29, a birthday shared by Benito Mussolini and Adaloisa Winkelmann, wife of the owner of the hotel.

Throughout the morning, a beefy man accompanied by a German shepherd straining at its leash patroled the front of the Hotel Tyll. Shortly before noon, identifying himself only as "Mr. Winkelmann's son-in-law, Magno," he ordered reporters to leave.

At his side, Frederico Eisendecher, identified as one of the participants in the April conference, flicked a whip nervously against his thigh. Suddenly, Magno's conversation was interrupted, as Eisenhower stuck out twice with the whip, leaving two blody marks on a photographer's arm, and uttered a command that caused the dog to leap forward and attack the half-dozen reporters, who withdrew to the edge of the road.

Hours later, Eisendecher and Alfred Winkelmann emerged from the hotel, dressed in identical dark blue uniforms. "This is a private meeting," Winkelmann announced. "So I am sure that I you will understand it when I ask you to leave."

A photographer took a picture, and Eisendecher again erupted: "Swine, filthy bastards," he hissed, striking out wildly and lunging at the photographer. Winkelmann turned on his heel and returned to the Hotel Tyll's dining room, where stylized swastikas served as wall decorations.

"We are not Nazis," said Magno in parting, "and even if we were, it wouldn't be a crime. This is a free country, thank God."

"The Kamaradenwek is anything but fiction," says Henry Sobel, a Sao Paulo rabbi who is one of Nai-zhunter Weisenthal's Brazil informants. "It is the international umbrella group that shelters all the subgroups and keeps them in touch with each other.

"Winkelmann's is one of the subgroups that exists in Brazil, but it is not the only one," adds Sobel. "There are other groups, more sophisticated more ogranized and more protected, that operate in the south and report, like the Winkelmann group, to the Kamaradenwek commands."

The head of the network is said to be Dr. Josef Mengele, whose experiments on prisoners at Auschwitz earned him the nickname "the angel of death." A Paraguayan citizen since 1959, owner of extensive land holding at Puerto Stroessner near Paraguay's borders with Brazil and Argentina, Mengele was named in a recent Amnesty International report as "technical adviser" to a government program described as designed to exterminate Paraguayan Indians.

Two other alleged Kamaradenwerk leaders, Kurt Manfred Richard Roeder and Hans Werner Shutte, were among the 16 people detained at Itatiaia in April. Roeder, who fled West Germany last year after being convicted of illegal Nazi activity, has since surfaced in Chile. Shutte, named in the German press as one of the key figures in a neo-Nazi group called "The German Reich Liberation Movement," is back in Germany.

"South America is a Nazi's paradise," Weisenthal once said, years ago. Nothing that has happened since has made him change his mind, at least in regard to Brazil: "Brazil is a virtual nest of Nazis," Welsenthal told reporters after Wagner's arrest in Sao Paulo was announced. "They just slip right into the populace and make themselves right at home."

Nazi activity in Brazil dates from the 1930s, when German bund groups sprang up in the far south of the country - Rio Grande do Sul, Santa Catarina and Parana. All three states had been settled largely by German Immigrants, who founded cities with names like Bluemenau, Westphallen and Nova Hamburgo: To this day, there are areas in the interior of Santa Catarina where German is still the dominant tongue.

The existence of this large German-speaking colony made Brazil fertile ground for the Abwehr, the Nazi intelligence agency. Dozens of Nazi spies - including Alfred Winkelmann, who had entered Brazil in 1935, ostensibly as a salesman of military equipment - were arrested and imprisoned when Brazil joined the Allies in 1942. But after the war, a new wave of immigrants flocked to German-speaking enclaves in the south, including some 4,000 SS and Gestapo officers, concentration camp guards and Nazi officials, according to one Brazilian account.

he official Brazilian government attitude toward the Nazi and neo-Nazi presence has been one of unconcern. The justice ministry has ruled that meetings of Nazis are not illegal, and Col. Ruben Ludwig, press secretary to Brazilian President Ernesto Geisel and, like his boss, a South Brazilian of German descent, recently dismissed the Itaitaia gathering as "nothing more than a get-together of nostalgic old men."

Given this position, Nazi supporters here make no secret of their sympathies: Jose Luiz Derkmann, for example, openly displays and sells jewelry with Nazi motifs - including swastikas - at his ship in Rio Grande do Sul. Residents of Santa Rosa, also in Rio Grande do Sul, awoke one morning early this month to find a Nazi flag flying form the flagpole in the main square. And in nearby Ijui, members of a group that claims to be linked to Winkelmann have daubed slogans such as "Free Wagner" and "The Reich Shall Rise Again" on walls of schools and synagogues.

"The Nazi spirit is merely sleeping in a good number of the inhabitants of this region," one former Wehrmacht soldier now living in Santa Catarina told a Brazilian newsmagazine last week. "All it needs to be awakened is one intelligent leader."

On Thursday afternoon, June 1, Gustav Franz Wagner sat in a reception room at the Sao Paulo headquarters of DOPS, Brazil's feared political police, his enormous hands, calloused and nicotine-stained, stabbing the air as he explained for the umpteenth time, in broken, German-ascented Portuguese, how he got from Treblinka and Sobibor to the interior of Brazil.

Dressed in the same baggy gray pants and sweat-stained work shirt he had been wearing two days earlier, when, fearing that Israeli agents were on his trial, he had turned himself in to Sao Paulo police, Wagner had been handed over to the press for questioning. It is a common enough procedure in Brazil, but Wagner, a shambling giant of a man, clearly objected.

The story he told, after his initial reluctance to talk gradually melted away into indifference, was full of contradictions and gaps. But it offered a rare and trantalizing glimpse into how the international Nazi underground may operate.

"When the war ended, I was in Italy, he said. "I went back to Austria, and one day Stangl and I met at a park in Graz. We talked for a while, and Stangl told me that he was going to leave Austria, leave Europe, for someplace quieter."

The conversation ended with the penniless Wagner being asked by his former commander to come along. "Everyone has a friend, a man they can rely on to carry out a task for them," Wagner explained. "For Stangl, I was always that man."

After several days of "waiting for things to be arranged," the two set out for Salzburg, Austria. From there, Wagner said, they crossed the Alps on foot, so as to avoid problems with border guards at the Italian-Austrian frontier, and made their way to Rome by train.

First stop in Rome was the Vatican. Having been told that Caritas International, a Roman Catholic relief organization was making passports available to displaced persons and refugees, Stangl and Wagner intended to assume new identities and slip away to some remote corner of the world.

"We had eaten and we were standing in line waiting to fill out some forms when a friend of Stangl's approached us. He told us that the Syrians were looking for ex-German army officers to train their new army."

At the consultate of the newly independent Arab state, Wagner said, he and Stangl were given Red Cross passports and a pair of plane tickets. After a stopover in Cairo, they proceeded on to Damascus, where they spent the next year.

"But then there was a change of government and the new president decided he wanted to use French soldiers, not German ones, to train the army," Wagner continued, "so the Syrians offered us money and passage out of the country." After contacting "friends" in the German colony in Damascus, Stangl told Wagner that it had been arranged for them to go to South America.

According to documents released by the Brazilian government after Wagner's arrest, the director-general of security in damascus issued a "safe conduct" passport to Wagner on Nov. 22, 1949. Two weeks later, Wagner obtained a visa from the Brazilian legation in Beirut, and on April 12, 1950, after a long sea voyage from Naples aboard the Conte Grande, Wagner still in the company of Stangl, disembarked under his own name in Rio de Janeiro.

For the next 28 years, Wagner lived in anonymity, working as a mechanic, first in Sao Paulo, later at a factory in Santa Catarina, and finally in Sao Paulo again.

"I used to go see Stangl at his house in Sao Paulo all the time," says Wagner. "Once I was even stopped on his doorstep by the police and asked to show my identifications. But Theresa Stangl came to the door and told them I was a friend, and that was that."

The visits ended in 1967, when Stangi, by then an executive at the Volkswagen do Brazil headquarters in a Sao Paulo suburd, was identified by a Jewish concentration camp survivor who had come to the plant looking for a job. Extradited to West Germany and convicted in Dusseldorf of war crimes on the basis of testimony given by Stanislaw Szmajzner, a Polish-born Jew and naturalized Brazilian citizen, Stangl died in a West German prison in 1971.

"When they arrested Stangl," says Wagner, I wanted to give myself up. But my wfie said to me "don't be foolish, Gustav. If they want you, they'll come and get you."

The host and his guests were singing the "Horst Wessel Lied" when police and reporters arrived at the Hotel Tyll at 6 a.m. on the evening of April 22. Their eyes were caught immediately by a poster of Adolph Hitler.

The poster was seized, as were the invitations that had been issued by Winkelmann. "As we did last year," said the invitation, "we cordially request your presence at the meeting of the friends of the 20th of April . . . also known as 'the meeting of the friends who have left from the same point of departure.'

"We will have announcements and news about emblems and titles of other circles of friends," the General-language document continued. "They, like us, wish to be not at last from yesterday, but rather the first for tomorrow."

To this invitation from "friends who have embarked from the same station," had responded members of groups as far-flung as the British Movement for Reich and Nation and the Argentine milita. More than half of them had departed by the time the police arrived, having had two full days to "exchange ideas about larger circles and important questions" at the Hotel Tyll.

The invitation had promise films but there were none to be found, and magazines it spoke of were there in abundance, including "Quotations From the Fuehrer" and "The End of the Lie of the 6 million." So too were records, "Flags on High" and "Song of Germany" among them.

Scattered among the rooms the "friends" had occupied were swastika decals and stickers with Nazi slogans. "Kauft Nicht Bei Juden" said one: "Don't Buy From Jews." "We Are Back: The Day Vengeance Is Come" said another.

But for those who wanted even more variety in their choice of Nazi paraphenalia, there was also a catalogue, in German, issued by a supply house that declared: "Donations on behalf of our common struggle will be gladly accepted." The address: Post Office Box 55A, Liverpool, W.Va. 25257 U.S.A.