Heim's file in the Berlin Document Center, the then-US-run depot for Nazi-era papers, was apparently altered to obliterate any mention of Mauthausen, according to his 1979 German indictment, obtained by the AP. Instead, for the period he was known to be at the concentration camp, he was listed as having a different SS assignment.
This "cannot be correct," the indictment says. "It is possible that through data manipulation the short assignment at the same time to the (concentration camp) was concealed."
There is no indication who might have been responsible.
The US Army Intelligence file on Heim could shed light on his wartime and postwar activities, and is among hundreds of thousands transferred to the US National Archives. But the Army's electronic format is such that staff have so far only been able to access about half of them, and these don't include the file requested by the AP.
Heim was relatively well-known, however, having been a national hockey player in Austria before the war, and there were plenty of witnesses from his time at Mauthausen.
Austrian authorities sent the 1950 arrest warrant to American authorities in Germany who initially agreed to turn him over, then told the Austrians, in a Dec. 21, 1950 letter obtained by the AP, that they couldn't trace him.
What happened next is unclear, but in 1958 Heim apparently felt comfortable enough to buy a 42-unit apartment block in Berlin, listing it in his own name with a home address in Mannheim, according to purchase documents obtained by the AP. He then moved to the nearby resort town of Baden-Baden and opened a gynecological clinic — also under his own name, Heister said.
In 1961 German authorities were alerted and began an investigation, but when they finally went to arrest him in September 1962, they just missed him — he apparently had been tipped off.
Heim continued to live off the rents collected from the Berlin apartments until 1979 when the building was confiscated by German authorities.
Proof that he is alive may lie in the fact that no one has claimed his estate. Heim has two sons in Germany and a daughter who lived in Chile but whose current whereabouts are unknown.
In Frankfurt, Heim's lawyer said he still officially represents the fugitive, but has not heard from him for 20 years and has "no clue" to his whereabouts.
Asked in a telephone interview if Heim was dead, Fritz Steinacker said only: "I don't know."
Ruediger Heim, one of the sons, would not comment when telephoned at his Baden-Baden villa.
"All I can say is that it has been implied that I am in contact with my father, and that is absolutely false," he said. "The rest is speculation, and I can't enter into that."