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.
Setelah kematian Otto Frank pada tahun 1980, buku harian asli, termasuk surat-surat dan lembaran kertas, diwasiatkan kepada Dutch Institute for War Documentation, yang melakukan studi forensik terhadap buku harian melalui Kementerian Kehakiman Belanda pada tahun 1986.