The painting’s owner only discovered that it depicted the infamous madam after a digital image search led her to the website for the book.
The writers had long been searching for the painting, which they knew existed from old photographs.
“I wrote to almost every auction house and antique dealer in Berlin. The fact that we found it is very important to us,” Schrammel said of their hunt for the painting.
“There are only a handful of photos of Kitty, and they are all in black and white.”
Brunner said the writers hope that the rediscovered oil painting will find a home in a museum, describing Madame Kitty and her brothel as “part of Berlin’s city history”.
The portrait appears to depict Madame Kitty in her 40s, although “she always pretended to be younger than she was”, Brunner told AFP.
“She was always very well-dressed and wore a lot of make-up.”
According to Brunner, it is unclear whether the brothel owner - who died in 1954 - had willingly worked with the Nazis or was forced into collaboration.
Brunner said she never joined the Nazi party and did not appear to hold anti-Semitic views - although “some of Nazi Germany’s biggest war criminals came and went at her home, and she got along with them”.
“She was probably a profiteer and an opportunist, but not a die-hard Nazi, according to what we know,” Brunner said.
- Agence France-Presse