Mr. Koophuis had met Mr. Frank in Amsterdam in 1923, when they both had business dealings there. This association continued intermittently until 1933, when the Franks moved to Amsterdam and the business relationship and personal friendship between the two men grew. In 1941, Koophuis took over Mr. Frank's place in the Travis company — otherwise, the firm would have been confiscated or liquidated as a Jewish business. It was Koophuis, together with Kraler, who proposed that the Franks use the back of the business building as a refuge. They helped the Franks move furniture and household items there, by stealth and at night, in order to avoid detection.
When a postcard reached the Franks in 1942, ordering Margot to report to the reception center at the Westerbork camp, everyone knew that the time to act had finally come. Mr. Koophuis was instrumental in ensuring that the secret of the group in hiding was kept, even though this raised many technical difficulties, particularly when the ownership of the building changed hands and the personnel in the warehouse also changed. Food had to be obtained for the group in hiding and paid for, extra food ration stamps had to be obtained, and in many cases, this aroused people's suspicions. Nevertheless, the baker, the vegetable man, and most of the other people with whom Koophuis had dealings, did not ask embarrassing questions; they simply cooperated in silence.
Mr. Koophuis has described the arrest by the Gestapo in the following words: "It was a Friday, and a fine August day. The sun was shining; we were working in the big office, Miep, Elli, and myself, and in the warehouse below us the spice mills were rumbling."
