In several investigations after the war, Van Maaren was the prime suspect for the betrayal of Anne Frank; however Van Maaren publicly denied he was responsible. Two other plausible suspects emerged over the years: Lena van Bladeren-Hartog (died 1963) and Tonny Ahlers (1917 - 2000).
There is a written record that somebody named “Ahlers” knew about Frank's hiding spot and how they had gone into hiding. Ahlers reportedly told his older brother, Cas, that he had betrayed the Franks during the war.
