BERLIN – A dogged Austrian filmmaker uncovered a massive underground Nazi complex in St. Georgen an der Gusen, Austria, which appears to be part of a secret atomic weapons development system.The Austrian daily Der Standard reported on Tuesday that documentary filmmaker Andreas Sulzer discovered a 1944 CIA report from an American spy that revealed the existence of a Nazi underground atomic weapon program in the area of St. Georgen an der Gusen. Radiation tests helped locate the exact site of the hidden atomic research complex.The small Austrian town, with a population of nearly 4,000, is located near the Mathausen-Gusen concentration camp. An entrance to the underground tunnel complex was found on the site of a shooting club in the small town.Samuel Laster, editor-in-chief of the Vienna-based “Die Jüdische” (The Jewish) website, told The Jerusalem Post on Sunday that the “filmmaker opened an important door that one has to go through.”Laster, an Israeli journalist who reports on Austrian Nazism, said cooperation from Austrian authorities and historians would be the best way forward to reach “historical truth.”“Prisoners from concentration camps across Europe were handpicked for their special skills – physicists, chemists or other experts – to work on this monstrous project,” Sulzer told the Sunday Times. “We owe it to the victims to finally open the site and reveal the truth.”He added that the site is “most likely the biggest secret weapons production facility of the Third Reich.”Nazi Waffen-SS helmets and other Nazi war merchandise were found at the location, which appears to be connected the Bergkristall Nazi armor site in St. Georgen an der Gusen.Bergkristall is believed to be the construction location for the Nazi’s jet fighter Messerschmitt Me 262.Following the discovery, the police stopped Sulzer’s archeological work, claiming he did not possess permission from the owner of the site. Sulzer disputed the police, saying he secured permission to investigate and dig at the location.According to media reports, Sulzer scoured archives in Russia, Germany and the United States for evidence of the Nazi program to build atomic weapons.