French far-right National Front founder Jean-Marie Le Pen arrives for a news briefing at party headquarters in Nanterre, near Paris, on Thursday. The executive committee decided to expel Le Pen from the party over remarks downplaying the Holocaust. Christian Hartmann/Reuters/Landov hide caption

itoggle caption Christian Hartmann/Reuters/Landov

Auschwitz survivor Eva Kor sits in a courtroom in Lueneburg, northern Germany, on April 21, 2015. She testified at the trial of 93-year-old former Auschwitz guard Oskar Groening. Julian Stratenschulte/AP hide caption

itoggle caption Julian Stratenschulte/AP

Jack Mandelbaum, a Holocaust survivor from the Polish city of Gdynia, poses in front of a photograph showing him as a youth. Tobias Schwarz/AFP/Getty Images hide caption

itoggle caption Tobias Schwarz/AFP/Getty Images

James Snyder, director of the Israel Museum in Jerusalem, with Egon Schiele's 1915 work, Krumau Town Crescent I. It's one of about 1,000 works of Nazi-confiscated art the museum has received. The museum has no record of who owned the painting before it was taken by the Nazis. In some 40 cases, the museum has returned artworks when heirs were found. Daniel Estrin for NPR hide caption

itoggle caption Daniel Estrin for NPR

Raphael Lemkin is the Polish lawyer and linguist who coined the term "genocide" — and dedicated his life to making genocide recognized as a crime. Copyright by Arthur Leipzig /Courtesy of Howard Greenberg Gallery, New York hide caption

itoggle caption Copyright by Arthur Leipzig /Courtesy of Howard Greenberg Gallery, New York

The names of Jeffrey Katz's family members are depicted on "stumbling stones" in Lembeck, Germany. His relatives owned a home on the property near the stones, before they were evicted in 1942. Jeffrey Katz/NPR hide caption

itoggle caption Jeffrey Katz/NPR