I must confess that reading the latest pages of this thread is an almost surreal experience.
The reason being that I am currently working in an archive looking at the Soviet investigation of Auschwitz in the spring of 1945, the raw materials for the official communique published at the very end of the war on May 7, 1945. Thousands of pages of material, numerous site inspections, medical reports, engineering reports, original German documents and of course, masses of testimonies. The commission interviewed 207 witnesses officially, but the files contain probably another hundred statements from other witnesses who wrote in to give their accounts, or were interrogated elsewhere.
Now let's place ourselves in the shoes of potential investigators of Auschwitz as of January 27, 1945. You find a massive camp complex, which you already know from various sources was a hell-hole. You find about 7000 survivors in various sub-camps, and hundreds more survivors make their way to the area after escaping the forced evacuation marches. What do you do? Do you simply ignore what all these people might tell you? Or do you do what any sensible investigation would do and find out from them what had happened there?
And so you hear about the crematoria, and the gas chambers, from hundreds of witnesses, most "ordinary" inmates, but some people who had actually worked inside the crematoria. Then you find in the captured documents some pieces of paper which clearly pointed to the same space described as a gas chamber by the witnesses being called a 'Vergasungskeller'.
On what planet, under what rules of criminal investigation, would the witness statements and the document not correlate?
I'm sure Saggy, or one of the other deniers here, will now try to tell me that all the files I'm reading cannot be trusted because they are "Soviet", and they'll try to tell me this
1) without having read the files
2) without reading Russian
3) without having any demonstrable grasp of Soviet history
4) without even thinking to do the elementary comparison with US, British, French, Czech, Polish, Dutch, Austrian etc investigations of the selfsame Auschwitz camp at the same time, i.e. 1945