Budapest, November 1944: Another German train has loaded its cargo of Jews bound for Auschwitz. A young Swedish diplomat pushes past the SS guard and scrambles onto the roof of a cattle car. Ignoring shots fired over his head, he reaches through the open door to outstretched hands, passing out dozens of bogus "passports" that extend Sweden's protection to the bearers. He orders everyone with a document off the train and into his caravan of vehicles. The guards look on, dumbfounded. Raoul Wallenberg was a minor official of a neutral country, with an unimposing appearance and gentle manner. Recruited and financed by the US, he went to Hungary to save Jews. He bullied, bluffed and bribed powerful Nazis to prevent the deportation of 20,000 to concentration camps and avert the massacre of 70,000 more in Budapest's Jewish ghetto. Then, on Jan. 17, 1945, days after Soviet troops moved into Budapest, the 32-year-old Wallenberg and his Hungarian driver, Vilmos Langfelder, drove off with a Russian security escort, and vanished forever. Because he was a rare flicker of humanity in the man-made hell of the Holocaust, the world has celebrated him ever since. Streets are named for him. His face has been on postage stamps. But researchers still wrestle with two enduring mysteries: Why was Wallenberg arrested, and did he really die in Soviet custody in 1947? And fresh documents are to become public that may cast light on another puzzle: whether Wallenberg was connected, directly or indirectly, to a super-secret US intelligence agency known as "the Pond," operating as World War II was drawing to a close and the Soviets were growing increasingly suspicious of Western intentions in eastern Europe. Speculation Wallenberg was engaged in espionage has been rife since the Central Intelligence Agency acknowledged in the 1990s that he was recruited for his rescue mission by an agent of the Office of Strategic Services, which later became the CIA. About the Pond, little is known. But later this year the CIA is to turn over to the National Archives a stash of Pond-related papers found in a Virginia barn in 2001. These are the papers of John Grombach, who headed the Pond. Despite dozens of books and hundreds of documents on Wallenberg, much remains hidden. The Kremlin has failed to find or deliver dozens of files, Sweden has declined to open all its books, and The Associated Press has learned as many as 100,000 pages of declassified OSS documents await processing at the National Archives. The Russians say Wallenberg died in prison in 1947, but never produced a proper death certificate or his remains. Independent research suggests he may have lived many years - perhaps to the late 1980s. If true, he likely was held in isolation, stripped of his identity, known only by a number or a false name and moved like a phantom among Soviet prisons, labor camps and psychiatric institutions. In 1991, the Russian government assigned Vyacheslav Nikonov, deputy head of the KGB intelligence service, to spend months searching classified archives about Wallenberg. Nikonov's conclusion: "Shot in 1947." Also in 1991, Russia and Sweden launched a joint investigation that lasted 10 years but failed to reach a joint finding. The Swedish report said: "There is no fully reliable proof of what happened to Raoul Wallenberg." The Russians concluded that "Wallenberg died, or most likely was killed, on July 17, 1947," and said they considered the case "resolved." ___ With the knowledge of his government, Wallenberg's task as first secretary to the Swedish diplomatic legation in Budapest was a cover for his true mission as secret emissary of the US War Refugee Board, created by President Franklin D. Roosevelt in a belated attempt to stem the annihilation of Europe's Jews. Some time around 1994, Susan Mesinai, who had by then been researching the case for five years, visited Lucette Colvin Kelsey, Wallenberg's cousin, at her home in Connecticut. Kelsey told her: "Raoul was working for the highest levels of government." "So I said to her: 'How high? Do you mean the president?' And she nodded her head," Mesinai said, disclosing to AP a conversation she had kept confidential for 14 years. In the 1930s, while he was a student at the University of Michigan, Wallenberg spent vacations at his cousin's home in Connecticut, where Kelsey's father was a well-connected former military officer and envoy to Sweden. Kelsey died in 1996. Wallenberg's rescue mission put him in a vortex of intrigue involving the Hungarian resistance, the Jewish underground, communists working for the Soviets, and British, US and Swedish intelligence operations. He also had regular contact with Adolf Eichmann and other Nazis running the deportation of Jews. Whether or not he himself was passing on intelligence, Russia had plenty of reason to suspect him of spying, either for the Allies or Germany - or both. "Wallenberg had ties to all the major actors in Hungary," says Susanne Berger, a German researcher who collaborated with the Swedish-Russian research project. The Stockholm chief of the War Refugee Board, Iver C. Olsen, was also a key member of the 35-man OSS station in the Swedish capital, and it was he who recruited Wallenberg. In 1955, Olsen denied to the CIA that Wallenberg ever spied for the OSS. Mesinai and Berger offer a different likelihood: that the Swede was a source for the Pond, which was known only to Roosevelt and a few insiders in the War and State departments. The Pond relied on hand-picked embassy personnel and contacts in private companies, particularly the Dutch electronics firm NV Philips, which had its own corporate intelligence network, said former CIA analyst Mark Stout, who wrote a brief unofficial history of the Pond. So far, no evidence has emerged Wallenberg worked for the Pond, and Stout said in an interview that Wallenberg isn't mentioned in any papers he has reviewed. ___ In December 1993, investigator Marvin Makinen of the University of Chicago interviewed Varvara Larina, a retiree who began working as an orderly at Moscow's Vladimir Prison in 1946. She remembered a foreigner in solitary confinement on the third floor of Korpus 2, a building used as a hospital and isolation ward. Though decades had passed, the prisoner stood out in Larina's memory. He spoke Russian with an accent and repeatedly griped that the soup was cold when Larina delivered it, she said. Prison authorities ordered her to serve him first. "This is very unusual," Makinen said in an interview. Normally, such complaints would condemn an inmate to a punishment cell. "The fact that he wasn't means he was a very special prisoner." When shown a gallery of photographs, Larina immediately picked out Wallenberg's - one never published, Makinen said. Larina recalled the man was in an opposite cell when another prisoner, Kirill Osmak, died in May 1960. Makinen and colleague Ari Kaplan created a database of cell occupancy from the prison's registration cards and found two cells opposite Osmak's that were reported empty for 243 and 717 days, respectively. Normally, cells were left vacant for a week at most, Makinen said. The researchers concluded the two cells likely held special prisoners, namelessly concealed in the gulag. Mesinai and others reviewed hundreds of accounts over the decades from people who claimed to have seen or heard of someone who could have been Wallenberg. They established a pattern of sightings from the reports, many unreliable, others uncorroborated, but some with a tantalizing ring of truth. One compelling account came in 1961. Swedish physician Nanna Svartz asked a Russian scientist about Wallenberg during a medical conference in Moscow. Lowering his voice, the Russian told her Wallenberg was at a psychiatric hospital and "not in very good shape." The Russian, Alexandr Myasnikov, later claimed he had been misunderstood, but Svartz stood firm. "He went pale as soon as he said it, and appeared to understand that he had said too much," she reported. If Wallenberg was alive after 1947, the question remains: Why was he never freed? The 2001 Swedish report speculated that the longer he was held, the harder it was for the Soviets to release him. "It might have appeared simpler to keep him in isolation." ___ Researchers continue to probe for Wallenberg's fate in Russia, and historians are awaiting the release of the Pond papers. Whatever any of this reveals, a 1979 U.S. State Department memo put the questions into perspective: "Whether or not Wallenberg was involved in espionage during World War II is a moot point at this stage in history. His obvious humanitarian acts certainly outweigh any conceivable 'spy' mission he may have been on."