Vatican officials have always insisted Pope Pius XII did everything possible to save Jewish lives during World War II. But many scholars accuse him of complicit silence while some 6 million Jews were killed in the Holocaust.

"Pope Pius XII thought that he should not take sides in the war," says Brown University professor David Kertzer, "and that therefore he should not be criticizing either side of the war, including the Nazis."

Kertzer has written extensively about popes and the Jews. He won the 2015 Pulitzer Prize for his book The Pope and Mussolini, which traced the rise of fascism in Europe. And he was among the first to have access to the Pius XII archives when the Vatican opened them in March, after decades of requests from scholars.

Kertzer has just published his early findings in an article for The Atlantic. The newly unearthed documents — some imbued with anti-Semitic language — are shedding light on the pontiff's behavior during the Nazis' massacre of Jews. They also reveal the pope's role in preventing orphans of Holocaust victims from being reunited with their relatives.

The historian found two documents that reveal an intense debate was under way in the Vatican in 1943, when the Nazi occupiers of Rome rounded up more than 1,000 Jews and detained them in a military college 800 yards from St. Peter's Square before packing them off to the Auschwitz concentration camp. As the German ambassador to the Vatican reported to Nazi leader Adolf Hitler, the roundup occurred under the pope's "very windows." Only 16 of the deportees survived.