A German TV documentary says Nazi war fugitive Aribert Heim died in 1992.
The Austrian doctor who sadistically killed hundreds of inmates at the Mauthausen concentration camp died of cancer in Egypt at the age of 78, according to the ZDF documentary.
The Nazi fugitive dubbed Dr Death is said to have spent his last 30 years in Egypt - some of them at this Cairo hotel.
Aribert Heim's fate after his wartime past as a sadistic killer of inmates at the Mauthausen concentration camp was a mystery.
Now an investigation by German broadcaster ZDF and the New York Times suggests he died from cancer in Egypt in 1992.
A ZDF documentary says he fled to Cairo to escape war crimes investigators.
He called himself Ferdinand Heim.
And he converted to Islam during the early 1980s, assuming the name Tarek Farid Hussein.
On his death he was buried in a pauper's cemetery where graves are freed up after only a few years.
The investigators say they have documents amassed by Heim, a death certificate, and confirmation by his son Ruediger that he had died.
But Nazi hunters at the Simon Wiesenthal Centre in Jerusalem say the findings lack conclusive proof.
SOUNDBITE: Efraim Zuroff, Simon Wiesenthal Centre, saying (English):
"There is no grave, there is no body, we can't do any DNA testing, and remember that there are people like his family who have a vested interest in convincing us that Heim is no longer alive."
At Mauthausen Dr Death is said to have killed hundreds of inmates by performing surgery without anaesthetic and injecting petrol into their hearts.
Among the local traders of Cairo, unaware of his past, some remember him almost fondly.
SOUNDBITE: Abd Al Samad Himawi, shopkeeper, saying (Arabic):
"He stayed at the Kasr el-Madina hotel maybe around 20 years ago and there was a roof space or something on the top and the kids would go there with him, probably the hotel owner's kids. They played with ping pong balls and when the balls fell down here he would come and get them."
Heim was the most notorious surviving perpetrator of the Nazi Holocaust and had a 1.2 million dollar price on his head.