Made me think back to Telegraph revealed Nazi gas chambers three years before liberation of Auschwitz:
It was under the headline “Germans murder 700,000 Jews in Poland”, that this newspaper reported the 'greatest massacre in the world’s history' on June 25, 1942. ... Zygielbojm succeeded in revealing the mass murder of Jews. But he was dismayed by the lack of public reaction. ... The Telegraph chose to report the “greatest massacre in the world’s history” on page five of a six-page newspaper. Zygielbojm’s informants were taking immense risks and their reports were meticulously accurate, yet he often encountered indifference, disbelief or even suspicion.
There you had reports of the extermination of 700,000 amidst an environment of wartime propaganda that would seem likely to make people more skeptical of reports. If you wonder how people might have managed to disregard this, consider the Iraqi case where many fell for reports of the death of half a million children which, if this later analysis is correct, never actually happened.