With Otto Frank's death in 1980, the original diary, including letters and loose sheets, was willed to the Dutch Institute for War Documentation, which commissioned a forensic study of the diary through the Netherlands Ministry of Justice in 1986.
Da Otto Frank døde i 1980, blev den originale dagbog, inklusiv breve og løse ark, overbragt til Det hollandske institut for dokumentation af krigen, hvor den gennemgik en kriminalteknisk undersøgelse under opsyn af det nederlandske justitsministerium i 1986.