German investigators said Thursday they want to search in Egypt for definitive proof that top Nazi war crimes fugitive Aribert Heim died there years ago after eluding capture for decades. New information indicates the Austrian concentration camp doctor lived in Cairo under an Arab name, learned Arabic and converted to Islam before his death from intestinal cancer in 1992. Heim was accused of carrying out gruesome experiments and murdering hundreds of Jews at Mauthausen concentration camp near Linz, Austria. Horst Haug, spokesman for the Baden-Wuerttemberg state police unit that investigates Nazi-era crimes, said his office received word earlier this week from a person "close to Aribert Heim" confirming the most-wanted fugitive died in Egypt. He would not identify the informant, saying only that "it was a serious source that we take earnestly." He added that his office is now working on a request to Egyptian authorities for German investigators to search there for proof of Heim's death. "We want to attempt to find the body," Haug told The Associated Press. Haug said his office is examining copies of 100 documents, believed to have belonged to Heim, found in a briefcase in the Cairo hotel where the SS doctor allegedly died. "We think it is plausible, but we can't give any official statement yet that Aribert Heim is dead," he said. German television station ZDF reported that Heim was buried in a cemetery for the poor in Cairo, where graves are reused after several years and so it is unlikely remains will be found. The new information in the Heim case came to light after ZDF, working with the New York Times, reported Wednesday that they had found the documents left by Heim in a briefcase in the Cairo hotel room where he lived under the name Tarek Hussein Farid. They included a passport, application for a residence permit and personal letters. Heim's son Ruediger Heim confirmed to ZDF that his father used the name Farid, and that the documents belonged to him. ZDF and the Times both posted a copy of the death certificate for Tarek Hussein Farid that was reissued for them last month. It confirms the date of death as Aug. 10, 1992 - the date cited by Ruediger Heim. The Simon Wiesenthal Center's head Nazi hunter, Efraim Zuroff, said Aribert Heim had previously been linked to Egypt, but the story raises "more questions than it answers." "There's no body, no corpse, no DNA, no grave - we can't sign off on a story like this because of some semi-plausible explanation," Zuroff told the AP in a telephone interview from Jerusalem. "Keep in mind these people have a vested interested in being declared dead - it's a perfectly crafted story; that's the problem, it's too perfect." Heim is at the top of the center's list of most wanted Nazis. Rainer Schopper, spokesman for the Linz, Austria, public prosecutor's office, said Austrian investigators were working with their German counterparts to "meticulously" verify the proof presented by ZDF and the New York Times. Heim escaped German authorities in 1962, and his son now says he fled through France and Spain before crossing into Morocco, and eventually settling in Egypt _ a country where ex-Nazis were welcomed. During World War II, there was widespread sympathy for Germany in Egypt, because many Egyptians hoped German forces would free the country from British domination. Anwar Sadat, who later became president and signed a peace treaty with Israel, was a prominent pro-German figure during the 1940s. In the 1950s, Egypt's President Gamal Abdel-Nasser took in a number of former Nazis, particularly to help train the military. In Cairo on Thursday, an Egyptian Interior Ministry official, speaking on condition of anonymity because he was not allowed to talk to the media, said authorities were investigating, but suggested it might be difficult to come up with any information. "The matter took place during another government's rule, many years ago, and no one in this government has a clue who that person was," the official said. "But authorities are working on investigating the whole case." "He died in 1992, said Tarek Abdel-Moneim el Rifai, son of Heim's dentist in Cairo. "I didn't know that he was a doctor and that he is the most wanted Nazi war criminal." El Rifai said Wednesday he hadn't seen the man for 20 years, but remembered that he never allowed himself to be photographed. The younger Heim told ZDF that he had met his father several times in Cairo, starting in the mid-1970s. He had failed in an attempt last summer to have his father declared legally dead so he could take control of an estimated â‚¬1.2 million in investments in his name, saying he could donate the money to charity. He told the AP he may try again to have him declared dead. Aribert Heim, born in 1914 in Radkersburg, Austria, joined the local Nazi party in 1935, three years before Austria was annexed by Germany. He later joined the Waffen SS and was assigned to Mauthausen, near Linz, Austria, as a camp doctor in October and November 1941. Heim was accused of taking part in experiments on Jewish prisoners, such as injecting various solutions into their hearts to see which was the quickest killer. He was indicted in Germany in absentia on hundreds of counts of murder in 1979. Karl Lotter, a non-Jewish prisoner who worked in the Mauthausen concentration camp's hospital, said he remembered the first time he saw Heim kill. An 18-year-old Jew had been sent to the clinic with a foot inflammation and Heim asked the boy why he was so fit. The young man said he had been a soccer player and swimmer before he was imprisoned, Lotter said. Lotter said Heim anesthetized the teenager and began operating on him but instead of treating the inflamed foot, he cut the young man open, castrated him, took apart one kidney and removed the second, Lotter said. The victim's head was then removed and the flesh boiled away so that Heim could keep it on display. Lotter's account of the 1941 atrocity was in a witness statement he gave eight years later, part of a 1950 Austrian warrant for Heim's arrest uncovered by the AP last year. "Of all the camp doctors in Mauthausen, Dr. Heim was the most horrible," Lotter said. The Heim case seems strikingly similar to that of another SS doctor - Josef Mengele - who eluded authorities to the end. Mengele, who conducted cruel experiments the Auschwitz death camp, drowned in Brazil in early 1979 and experts identified the body as his six years later. At the hotel where Heim allegedly lived until his death, the shabby Kasr El Madina Hotel in a commercial area in downtown Cairo, a daughter of the owner screamed at reporters on Thursday and refused to allow anyone inside. She refused to give her name but said it all happened a long time ago and they had nothing to do with it any more.