How did Otto Frank help arrange for their hiding place?
Otto Frank own the warehouse they hid in until Amsterdam was taken over. He knew of the hiding place way before the war.
Someone who worked at the building they were hiding in. There was another family that was hiding out with the Frank family. In Anne Frank's diary she never did reveal the name of the so-called rat amongst them. Someone who was robbing them was arrested and he told the gastapo that they were living there.
Otto Frank and his family were Jewish. At the time that the Frank family went into hiding, the Nazis were gathering up all the Jews and sending them off to concentration camps or work camps. Anne, Otto's daughter, had received a notice that she was to report to a work camp. Rather than see his daughter, and probably the rest of his family as well, go into work camps, Otto chose to go into hiding…