As Brazilian investigators prepared to begin major forensic work on remains alleged to be those of Nazi war criminal Josef Mengele, the man who claims to have sheltered him for the last years of his life provided new details today of what he said was Mengele's time in Brazil under an assumed identity.

Wolfram Bossert, 59, and his wife, Liselotte, 57, in an interview at a secluded forest hut that they said Mengele sometimes visited, denied having been in contact with any international network of postwar Nazi protectors.

"If an organization of Nazis really exists, then they should be ashamed not to have found any other protection or shelter for Mengele than a Hungarian couple or myself, who had nothing to do with it. I was 19 when the war ended," Wolfram Bossert said, denying that any organization had contacted him during the period he claims to have protected the war criminal.

The Bosserts claim to have sheltered Mengele at their farm from 1975 to February 1979, when, they say, he drowned in a swimming accident.

The search for Mengele began to focus on Brazil after West German police found a cache of letters last month leading them to a grave exhumed Thursday outside Sao Paulo. Officials have said that examination of the remains is expected to take up to three weeks.

Opinions of officials and private Nazi hunters about the new clues to Mengele's whereabouts in the 1960s and '70s have varied, and extensive police work remains before the claims about the life and death in Brazil of the man alleged to have been Mengele can be verified.

West German experts in Brazil said they believe the remains are Mengele's, according to a report today in a West German newspaper, but an Israeli government spokesman said Israel would continue efforts to catch the Nazi war criminal, news agencies reported.

"I've heard of the Odessa," Bossert said today, referring to an organization believed to have helped spirit Nazis out of Europe after the war. "It probably existed, because Mengele obviously left Germany with someone's help. But I can guarantee that in our case there was no contact with anyone -- I was alone with Mengele.

"Perhaps that's the reason why he was never discovered. If the circle had been wider then he could have been found."

Bossert said Mengele, who had assumed the identity of an Austrian named Wolfgang Gerhard, was paranoically shy and would never go out without wearing a hat because he had been told that he had a very distinctive forehead. On the street he imagined that everyone was watching him.

"He wasn't so stupid to risk his life," Bossert said. "He was very cautious. He was the most sought after man in the world.

"He had a tremendous will to live -- that's why he survived so long. He used all means available to ensure his security and protection," Bossert said.

"He was a very intelligent man -- don't forget he was an SS officer. Sometimes he'd sit and think about all the possibilities. When there was a news article about him he'd sit thinking for hours, about where the news came from and if it was true or a police plant."

Mengele, who was known as the "Angel of Death," conducted gruesome medical experiments on inmates, particularly children and twins, at the Auschwitz concentration camp in Poland and sent hundreds of thousands of Jews, Poles, Gypsies and other prisoners to their deaths.

"I admired him as a person for his many good qualities, not for what he had committed. And even today there's doubt as to whether that's really true," Bossert said in response to a question about the Auschwitz atrocities.

"Once you know someone well and become friends, someone who likes nature, children, animals and is interested in literature and philosophy, it becomes very difficult to believe that this person could have committed such cruel crimes," Bossert said, speaking with a heavy German accent. "The police tell me that many criminals seem like angels -- but I'm still in doubt.

"It's easy to say that knowing a criminal every citizen has an obligation to denounce him. But if you know someone intimately even if he's a wanted man -- I just couldn't do it," said Bossert, who admitted that he had been a member of the Hitler Youth but minimized its importance.

Mrs. Bossert said her children called him titio -- uncle. "He told them of his infancy and stories from the past, of Greece and Rome -- the children adored him."

When her husband said Mengele had lived so simply that sometimes he used torn or frayed clothes, she quickly interrupted to say that she had sewed for him. She said she had been dismissed last week from her post as a teacher after the revelations about the couple's alleged connection with Mengele.

The Bosserts emerge as retiring, modest and loyal to what they perceived as the good points in the man they believe was Mengele.

Though she arrived in Brazil in 1952, Mrs. Bossert's Portuguese is rudimentary. She seemed confused by her dismissal from the school, which news reports said followed pressure from parents of students.

Bossert said he doubted the assertions of a dentist in Sao Paulo who said that she had treated an irascible German named Muller of outspoken racist views whom she had identified from pictures supposedly of Mengele. "He'd never have said anything incriminating to a stranger," Bossert said.

"He told me of an attempt to have plastic surgery in Argentina or Paraguay but complained the man was incompetent and had left a scar. He'd been trying to raise the brow. He'd also tried to change the position of the front teeth, which were far apart. But they got spoiled and afterwards he complained always about his teeth. Only very late on did he get a dental plate made."

He said that when he wrote to Germany advising Mengele's family of Mengele's death and the burial Feb. 8, 1979, "I said probably they'd agree to maintain the secret. They replied in a letter that naturally the case was much too dangerous to be revealed and that much water would have to flow under the bridge before this could be exposed. So I kept the secret.

"The contact was Hans Sedlmeier," Bossert said. Sedlmeier is a former employe of the Mengele family firm in Guenzburg, West Germany, and the man the Bosserts claim was Mengele reportedly had received sporadic payments of dollars from him.

"Sedlmeier brought money once, but it was never a regular thing," he said, adding that one remittance could have been $10,000.

Part of this money had been invested in a small farm at Caieiras, where he had lived with his first protectors in Brazil, the Hungarian couple Geza and Gitta Stammer. Gitta Stammer's testimony to police Friday corroborated some details provided earlier by the Bosserts.

The Bosserts said Mengele was responsible for restoring farm buildings, and when the farm was sold the Stammers made regular payments to Mengele for his half-share. "He didn't spend anything -- he worked for his food."

Bossert said Mengele's son Rolf had managed to outwit police tailing him by entering Brazil in 1977 and 1979 on a false passport. "He's a very intelligent lawyer and on the way to us he changed taxis several times."

The Bosserts were brought by police to the farm near Juquitiba, 50 miles outside Sao Paulo, where Wolfgang Gerhard, the man whose identity the Bosserts say Mengele assumed, and his family had lived for eight years before returning to Austria, where he died.

The 20-acre farm set in a remote wooded valley reached by a quarter-mile overgrown track, was visited twice yearly by Mengele, according to Bossert.

Bossert showed books in Portuguese he said had belonged to the man they said was Mengele. One -- "And The World Forgot" -- was by Van Abraham, an Auschwitz survivor. Other books included "The Fourth Reich" and a "QB VII," a Leon Uris novel about a former concentration camp doctor working in North Africa who is found out and brought to trial.

"He was interested in books in which he appeared and about the place where he'd worked," Bossert said. He claimed Mengele also received medical and biology textbooks from Germany.

Bossert said the real Gerhard, who had passed on his identity documents to Mengele and then died at Graz in Austria in 1978 under what he called "funny circumstances," was a Nazi and "a bit fanatic." He had been a member of the Hitler Youth.

"He spoke of the Hitler Youth -- but everyone participated in that. Even I was a junior leader," Bossert said. He said Gerhard, who had first introduced him to Mengele, had been "very astute in testing us out to see if we were the kind of people who might denounce someone. He soon realized that threats wouldn't work; I'm different than Stammer," who he said had been threatened to keep silent.

United Press International reported today from Brazil:

Forensic experts armed with German dental records were set to begin tests Monday on the remains exhumed from a grave at Embu, Brazil, Thursday.

Experts from Brazil's Medical Legal Institute are expected to take until the end of the month to complete the tests and have turned down offers of help from the United States, West Germany and Israel.

West German police sent to Brazil believe the remains are Mengele's, the West German newspaper Die Welt said today in a dispatch from Sao Paulo.

"On the basis of current expertise, it must be assumed that the body buried on Feb. 8, 1979, under the name of Wolfgang Gerhard is that of Josef Mengele," one of the unidentified German detectives said, according to the newspaper.

In New York, Nazi hunter Simon Wiesenthal said today that there was a 50-50 chance that the body was that of Mengele, warning that it may be part of a hoax designed to end the search for the infamous doctor. "If the body is not Mengele's, there is the argument that he is alive and this is a family plot," he said.

In Tel Aviv, an Israeli government spokesman said that while the Brazilian tests are being conducted, Israel "would continue its efforts to catch Mengele and bring him to justice in Israel."

Menachem Russek, head of an Israeli police detail charged with investigating Nazi war crimes, told Israeli radio he believes Mengele is behind the reports of his death in a desperate attempt to stop the worldwide manhunt for him.

Conflicting information in the past few days has created doubts about whether the remains buried under the name of Gerhard are actually those of Mengele.

The coroner who examined Gerhard after the drowning said he saw no reason to question the victim's age on his identity card -- 54 -- which would have made him 14 years younger than Mengele would have been in 1979.

Morgue chief Rubems Maluf and coroner Jose Antonio de Mello said they plan to begin the forensic investigation by cleaning the bones and rebuilding the skeleton. But only positive identification can come from 1938 dental records provided by West Germany. The remains exhumed Thursday contained seven natural teeth, two dentures and a gold crown or capping.

"If any of these teeth were treated in Germany, then the records could be of great value," de Mello said.