Niedereitter's parents were from Sarata, Bessarabia, as shown here and here. His profile on Revisionists.com implies they were still in that location when Wilhelm was born, but then moved to German soil:
Sanning is a scholar and businessman who was born in 1936 into an ethnic German family in an area that for decades was a part of the former Soviet Union. After a childhood in wartime Germany, he migrated in the 1950s to the United States, where he met his wife. He graduated from a prominent Pacific Northwest university with a bachelor's degree (high honors) in business.The location in "wartime Germany" was actually in the Warthegau, in Kreis Pleschen, where Sanning's brother was born in 1943. The fact that Sanning's ancestors fled Bessarabia for the Warthegau just prior to the former coming under Soviet occupation may have motivated Sanning's desire as an adult to minimize the Nazis' genocide of the Jews. In the 1950s, Sanning was studying at the Kinman Business University in Spokane, where he met his wife Carol Ann Lindquist, whose obituary is here. The couple moved to Frankfurt, Germany, in 1970. As of 1987, a man known as Wilhelm Niederreiter was "manager of economic research at the Dresdner Bank", as shown here. It is possible, although it cannot be proven, that this was the same man who wrote as Sanning, although the report about Dresdner describes him as having a PhD, which seems very unlikely. Niederreiter was still living in Germany as of July 2014, when his wife died in Friedberg.
Hopefully, this article will end any misconceptions about Sanning's death, and shed some light on how and why Sanning entered the world of denial before abruptly leaving it. His interest in "demographics" and his motivation to downplay the numbers who died in the Holocaust were both likely caused by his childhood experiences, as he would have viewed his family being "liberated" from Soviet occupation and resettled in the Warthegau. His decision to leave the denier world may have been due to his job at the bank, or fear of exposure in a country where denial would eventually be criminalized. His book is ludicrous but his life is an interesting case study of a particular population of Volksdeutsche who have embraced pro-Nazi positions at various points since 1945.