Research by the Anne Frank House museum shows that the famed World War II diarist is likely to have died earlier than previously thought.

The conclusion was published on the 70th anniversary of the official date of the deaths of Anne and her sister Margot as decided by Dutch authorities after the war. But researchers Erika Prins and Gertjan Broek say the pair likely died of typhus in February 1945.

Anne’s diary about her life in hiding during the war has made her a symbol for the suffering of Holocaust victims.

The research, based on witness accounts, documents and at least one interview, underscores the horrific conditions Jews endured in the Bergen-Belsen camp where Anne died atof 15.