BERLIN, Germany (CNN) -- One of the world's most wanted Nazi war criminals died 17 years ago in Egypt, the German public broadcaster ZDF reported Wednesday.
The network says research it conducted with the New York Times shows that Aribert Heim died in Cairo in 1992, according to ZDF's Web site.
The chief Nazi hunter at the Simon Wiesenthal Center, Efraim Zuroff, said the news, if true, is deeply disappointing.
"I personally feel a tremendous sense of disappointment that he escaped justice," Zuroff told CNN.
But he emphasized that he had not seen the evidence that Heim was dead.
"There is no body and no grave, so we can't do a DNA test," he said, adding that "there are people who have a vested interest in convincing us that he is no longer alive."
He said he expects to see the documentary evidence of Heim's death on Thursday. Heim would be 94 years old if he were still alive.
Zuroff described Heim as "the most wanted Nazi war criminal," and said the Simon Wiesenthal Center was about to raise the reward for information about him from 315,000 euros ($405,000) to 1 million euros ($1.3 million) when it heard the reports of his death.
The investigation found that Heim lived under the false name of Tarek Farid Hussein in Cairo until August 10, 1992, when he died of intestinal cancer.
ZDF says that eyewitness accounts as well as documents prove that Tarek Farid Hussein was in fact Aribert Heim.
During World War II Heim was a doctor at the Mauthausen concentration camp, where he was known to inmates as "Dr. Death" for performing often-fatal experiments on prisoners.
After the war, he was initially cleared of wrongdoing, but in 1962 German authorities issued an arrest warrant for him.
ZDF says it has spoken to Heim's son, Ruediger Heim, who told the broadcaster that his father fled Germany to Egypt via France, Spain and Morocco.
Ruediger Heim told ZDF that he visited his father in Cairo several times, including in the final weeks of his life when the terminal cancer was discovered.
ZDF says that a passport belonging to Aribert Heim was among documents it retrieved.
CNN Berlin Bureau Chief Frederik Pleitgen contributed to this report