An interesting read. It seems to indicate that Pius XII knew more about the Holocaust than the Vatican admits. This letter to Pius XII from a trusted priest was buried in the archives. Letter shows Pope Pius XII had detailed information from German Jesuit about Nazi holocaust
A quote from the article, helpfully buried midway through: "While it can’t be certain that Pius saw the letter..."
I'm not sure the pope's secretary would keep such explosive contents from the pontiff. Taken in conjunction with the following passage from the same article: ... it would appear that if the pope was ignorant of the mass murders occurring, it was willful ignorance.