Yad Vashem, Jerusalem’s memorial to the six million Jews murdered by the Nazis during World War II, also recognizes non-Jewish individuals who risked their lives to save the Jews from the Nazi executioners. One of the trees that line the memorial’s “Avenue of the Righteous” was planted to honor Raoul Wallenberg, a Swede. Among the bravest heroes of World War II, he saved about 100,000 Jews.

But when the war ended, Wallenberg did not return home to well-earned acclaim. Instead he was arrested by the Soviet troops who marched into Budapest. The Soviet government has declared time and again that he is dead. And, just as often, new witnesses have insisted that Raoul Wallenberg is–or was–still alive in a Soviet prison or a mental hospital.