Peter Van Pell was 17 when Anne Frank died.
Anne frank was 15 years, eight months and a few weeks old when she died of Typhus. She died in early March 1945 at Bergen-Belsen concentration camp.
He published her diary in 1947 as The diary of a young girl.
He published it, with the help of Miep.
Anne Frank was 16 when she died.
She was 13 when she started writing it, and 15 when she stopped writing in it (when she got captured).