In the late 1940 Otto Frank's warehouse man Willem Van Maaren was under the investigations. Due to the lack of evidence the process was stopped, but opened again in the 1960s. No evidence was found. In the 1980s a new name came up: Lena Van Bladeren, who worked in the office as a cleaning woman. Carol Ann Lee has claimed that Otto Frank's business friend, Tonny Ahlers, who helped him to continued his spice trade from the hiding place, betrayed the family. Tonny Ahlers was a member of the Nazi party.
However, all three persons were cleared of any suspicons because lack of hard evidence. While offically cleared, Ahlers, the most nortorious of the lot was also thought to be the most likely, it was documented that Ahlers's brother and son, Cas and Anton, admitted to hearing Ahlers's confession to the repugnant deed.The betrayal of Anne Frank and her family will never truely be completely uncovered, it will remained one of the sad mysteries of the second World War.