Top Nazi hunter Efraim Zuroff urged the German government on Wednesday to examine how one of the world's most wanted Nazis was able to hide in Egypt until his apparent death in 1992. Zuroff, of the Simon Wiesenthal Center, said new information that surfaced last week about SS doctor Aribert Heim - the most wanted Nazi war criminal on his organization's list - suggested that German authorities might have let him slip through the cracks. Among other things, Zuroff cited a 1981 application where Heim applied for an extension to his residency permit in Egypt, using his German passport number and indicating his German citizenship. "Officials must have noticed that Heim was being sought," Zuroff said in a statement. In the application, however, Heim went by an alias - Tarek Farid Hussein - and it is not clear whether German authorities were consulted. German Foreign Ministry spokesman Jens Ploetner said the government was looking into the case. "This is in relation to concrete events that go back to the early 1980s," he told a regular news conference. "We take what the Simon Wiesenthal Center says very seriously and we will very thoroughly examine the questions brought up by the Simon Wiesenthal Center." Heim was accused of carrying out gruesome experiments and murdering hundreds of Jews at Mauthausen concentration camp near Linz, Austria. New information reported by The New York Times and German broadcaster ZDF indicated that the Austrian-born concentration camp doctor lived in Cairo for decades under an Arab name, learned Arabic and converted to Islam before his death from intestinal cancer in 1992.