In July 1942, Frank went into hiding in the same building, together with his wife Edith Holländer and his daughters Margot and Anne, later accompanied by the van Pels family and dentist Fritz Pfeffer.
Furthermore, in August 1942, Voskuijl built the famous bookcase that concealed the entrance to the Secret Annex.
He also made Saint Nicholas gifts for the people in hiding, such as an ashtray for Hermann van Pels, a picture frame for Pfeffer, and bookends for Otto Frank.
[1] The people in hiding felt a great loss when Voskuijl had to stop working in the summer of 1943, as he suffered from stomach cancer.
On 15 June 1943, Anne Frank wrote: "It is a disaster for us that good old Voskuijl won't be able to keep us in touch with all that goes on, and all he hears in the warehouse.