Heim was wanted for killing hundreds of concentration camp victims with horrific medical experiments, including performing operations without anaesthesia and injecting petrol directly into their hearts.
Leading Nazi hunter Efraim Zuroff from the Simon Wiesenthal Centre had said last July that he believed Heim was still alive and hiding out in either southern Argentina or Chile. However, ZDF said it had uncovered he died of cancer in 1992, citing Heim's son and acquaintances in Egypt, where he had been living under a false identity after converting to Islam.
The New York Times, which received documents along with ZDF from the owners of the hotel where Heim lived for years undetected in Cairo, said there was a certified copy of a 1992 death certificate obtained from for a man called Tarek Hussein Farid.
"Tarek Hussein Farid is the name my father took when he converted to Islam," his son, Rüdiger Heim, told the newspaper. He also admitted that he was with his father in Egypt when he died from rectal cancer.
On Wednesday, Zuroff said that the German TV report sounded authoritative but that he would rather wait for confirmation before passing further comment. "I don't want to comment just yet. The reports seem to be serious but I'm still waiting for confirmation from my own sources and there are various questions that need to be answered," he said.
Heim was number two on the most wanted Nazi list, after Alois Brunner, Adolf Eichmann's main assistant, who is thought to be dead.
Born on June 28, 1914, in Radhersburg, Austria, Heim joined the Nazi party before Austria was annexed by Germany, when membership of the party was still illegal. He then became a member of Hitler's elite SS guard in 1940 and, after stints at camps in Buchenwald and Sachsenhausen in Germany, was posted to the infamous Mauthausen camp in Austria.
It was at Mauthausen that he became known as "Doctor Death" after performing his sadistic and grotesque medical experiments. Survivors of Mauthausen allege the father of three cut prisoners open, removing their livers and other organs.
His cruelty was such that he has frequently been compared to Josef Mengele, the so-called "Angel of Death" who was a doctor at Auschwitz.
Zuroff, who has been leading the search for Heim, said in July he had to be brought to justice, whatever his age.
"He castrated people, he used parts of their body to decorate his office. I'm not giving out these details to emotionalise the issue, but for people to understand how important it is to catch this criminal," Zuroff said.
Heim was arrested by US troops in 1945 but was released two and a half years later. He subsequently set himself up as a gynaecologist in Germany but fled in 1962 when authorities were poised to arrest him.
There had been numerous reported sightings of him as far afield as South America, Egypt and Spain. Nazi-hunters thought twice in recent years they were close to pinning him down, once in Spain in 2005 and again last year in a small Chilean town some 1,000 kilometres (600 miles) south of Santiago.