The heirs of a Jewish man who died in the Theresienstadt concentration camp in the current Czech Republic are demanding the return of his multimillion-dollar painting by Egon Schiele, which is in Christie’s auction house in Manhattan, according to a civil suit filed in Manhattan on Thursday.

The painting, titled “Portrait of the Artist’s Wife,” had been seized from Dr. Heinrich Rieger in Vienna, Austria, by the Nazis, who considered Schiele’s work “degenerate” art because it depicted nude women, according to the suit.

The work is owned by the Lehman Foundation — the fine art collection owned by the now deceased banker Robert Lehman — and is being consigned by the organization at the high-end auction house near Rockefeller Center.

It’s worth between $5 million and $7 million, according to the suit.

Rieger’s heirs found out the artwork was controlled by the foundation and filed a demand to return the piece on April 13, 2019. The foundation refused, according to the suit.

If the foundation does not return the piece, the heirs are seeking to recoup the millions of dollars that they claim the painting is worth, the suit states.

Lawyers for the Lehman Foundation did not immediately return request for comment.