Dr. Aribert Heim, who died in Cairo back in 1992, was aided by his son Rudiger Heim, The Daily Telegraph reported Thursday.
The newspaper said he will avoid criminal charges for hiding his father because German law excuses people from giving evidence against their family members.
Heinz Heister, a judge at the regional court of Baden Baden, where Rudiger Heim lives, said the son was under no obligation to speak out.
"He was within his rights to say nothing because he is the son. That is the law in Germany: You can say nothing if it is about a family member," he said.
Known as "Doctor Death," Heim was wanted for killing hundreds of prisoners at Buchenwald, Sachsenhausen and Mauthausen concentration camps by performing gruesome medical experiments, including removing organs from victims without anesthetic and injecting poisonous liquids such as gasoline into their hearts.
After the war, Heim lived in Baden-Baden, Germany, where he had a wife and two sons, The New York Times said. He wound up in Egypt, where he died.
Heim was born June 28, 1914, in Radhersburg, Austria, and joined the Nazi party before Germany annexed Austria.