Norbert Klein was a German Jew who had fled the country. He was part of a group of Palestine pioneers or HeHalutz, emigrants who had come to the Netherlands to prepare for living and working in Palestine. After the German invasion, they were prosecuted. Many of them were arrested during various raids in 1941, but the HeHalutz had also formed a resistance organisation, in close cooperation with the Dutch.
Norbert Klein was responsible for finding hiding addresses and escape routes. He was ‘half Jewish’, so he did not have to wear a Star of David. He was arrested in September 1943 and that was how the names of his friends in Germany came into the hands of the Sicherheitsdienst. His friends were warned in time.