Since the late 1940s, the files of the United Nations War Crimes Commission which includes evidence of Nazi crimes during World War II were sealed. Researchers wishing to read some of the files needed permission from their national government or the Secretary General of the U.N. and were not allowed to make copies or even take notes while reading the documents. But this Friday, those tens of thousands of pages of documents, about 900 gigabytes worth of data, will be made public, reports Owen Bowcott at The Guardian.

While the vast trove of material promises to keep historians busy for years, there are some intriguing revelations already coming out of the documents, such as proof that the Allies were aware of the scale of the Holocaust as early as 1942. It was commonly thought that though the Allies understood that Jews were being persecuted under the Nazi regime and heard rumors about the camps, most officials and military leaders did not understand the scale of the genocide until the camps were liberated in the summer of 1945.

But Dan Plesch, author of the new book Human Rights After Hitler, who campaigned for the commission's archive to be made accessible to the public, and was given special access to the documents for his research, tells Andrew Buncombe at The Independent that the U.S. and U.K. had intelligence in December of 1942 that two million European Jews had already been murdered, and that five million more were at risk from the Nazis. That same month U.K. foreign secretary Anthony Eden told Parliament that the Germans were carrying out their threat to exterminate the Jewish people.

“The major powers commented [on the mass murder of Jews] two-and-a-half years before it is generally assumed,” Plesch tells Buncombe. “It was assumed they learned this when they discovered the concentration camps, but they made this public comment in December 1942.”

Bowcott reports that the information about camps like Auschwitz and Treblinka was smuggled out of Eastern Europe by the Polish government in exile. The Czech government in exile also provided reports of massacres committed by Nazi units in their country as well. There was enough information that the United Nations, established in January 1942, had already drawn up war crimes charges against Hitler as early as 1944.

There are other revelations in the documents as well, including the fact that war crimes including rape and forced prostitution were being prosecuted by tribunals in Greece, the Philippines and Poland in the 1940s.

“We anticipate a lot of interest. Some of the PDF files each contain more than 2,000 pages," Howard Falksohn, archivist at the Wiener Library, which specializes in Holocaust studies and is hosting the documents, tells Bowcott.