What exactly are you talking about?
Post a link if possible, I am just curious.
The museum contains seven paintings by an inmate, Dina Gottliebova Babbitt. Ms Babbitt spent 33 years attempting to recover the paintings and wanted them to be placed in them in Holocaust museums in the United States (Auschwitz-Birkenau Museum displayed at that time only copies (for security reasons) and still rotates between displaying originals and copies). The position of the museum was that they legally bought the paintings but then when it became clear under international law that merely buying stolen art work in good faith did not give any rights to it, they changed tack and invoked the legal principle of 'work for hire': the concept that the patron, not the artist, holds the rights to a commissioned work of art. Their stance is that Dr Mengele commissioned the work and so only he has the right to them. As he doesn't want them, they belong to the Polish state. In 1973 the museum wrote to Ms Babbitt saying "if anyone has a right to these paintings, it's Dr. Mengele, but I doubt he will pick them up."
The position of the museum can be found here. News articles about Ms Babbitt are here, here and here. There's a copy of a letter from the museum from January of this year in which they repeat their stance that "the portraits
of Gypsies made in the camp by Mrs. Dina Gottliebova-Babbitt have never
been her property".
Got to love a museum which considers the rights of the sick bastards who carried out the holocaust as more important than the rights of the victims of the holocaust.