Organisers of the Baantjer walking tours in Amsterdam said they had found a unique photograph of detective and writer Appie Baantjer in the National Archives. The photograph reportedly shows Baantjer investigating the 1958 murder of the sex worker Finnish Hennie and is, as far as is known, the only image of him working on a case. Baantjer later became known for his books about De Cock in the 1960s.