In April 1944, Rudolf Vrba and Alfred Wetzler, two Slovakian Jews, fled from Auschwitz, where they had been held since 1942. They crossed into Slovakia and found shelter in Žilina, where they authored a long report about Auschwitz, with many details about the Holocaust. Copies of the report soon circulated around the world.

092 – Rudolf Vrba on his escape from Auschwitz

During the years [in Auschwitz] when we [Vrba and Wetzler] were forced to watch all our friends and acquaintances from Trnava [Wetzler’s hometown] being murdered or succumbing to the conditions in the camp, we became close friends and trusted one another. This mutual trust was the precondition for the many small steps that were necessary to prepare our escape. There was no “resistance group” or “organization” that was responsible for deciding that we should make a break for it or which way we should go, assuming we succeeded in surviving the search which was organized after every escape. […] Our plan envisaged us hiding in the as yet unfinished sector BIII in Birkenau, roughly 300m east of Crematorium V. We only left Birkenau on 10 April after the conclusion of the intensive three-day hunt following the discovery of our disappearance. After various incidents we succeeded in crossing the Slovak border on the morning of 21 April, a Friday.[…]

​ For hours I dictated my testimony

[On] April 25 [1944], [Alfred] and I were sipping sherry at the Zilina headquarters of the Jewish Council […]. For hours I dictated my testimony. I gave them detailed statistics of the deaths [in Auschwitz]. […] I explained the machinery of the extermination factory and its commercial side, the vast profits that were reaped from the robbery of gold, jewellery, money, clothes, artificial limbs, spectacles, prams, and human hair which was used to caulk torpedo heads. I told them how even the ashes were used as fertiliser. I gave them, in fact, the whole ghastly picture, the information I had been gathering so carefully for so long […]. I sagged back in my chair and I felt weak, not because of my journey from Auschwitz and the strain of it; not because I had been talking for hours, stripping my mind and my heart; but because relief suddenly struck me with all the force of a physical blow.

Source: R. Vrba, “Die missachtete Warnung”, Vierteljahrshefte für Zeitgeschichte 44 (1996), pp. 6–7, translation by Lesley Sharpe and Jeremy Noakes; R. Vrba, I Cannot Forgive (Vancouver, 1997), pp. 248–9