Simon Wiesenthal, a famed Nazi hunter and Holocaust survivor, died Tuesday. He was 96.

Wiesenthal doggedly pursued war criminals involved in German atrocities which claimed the lives of 6 million European Jews during World War II. He may be best remembered for his sometimes-disputed role in the pursuit of Adolph Eichmann, one of the architects of Hitler’s Final Solution, and of Gestapo thug Karl Silberbauer, who arrested young diarist Anne Frank in Amsterdam. Frank later died in a Nazi death camp. His research also uncovered the underground railroad that the Nazis used to ferry fugitives out of Europe after Germany’s collapse, and helped with the capture of some truly terrible people. Even those Nazi murderers who escaped discovery and arrest knew that Wiesenthal was determined to find them. They could never be sure the next knock at the door wouldn’t be the local authorities or Israeli agents acting upon a Wiesenthal-created dossier.

During the Cold War, when the United States and the Soviet Union actively recruited former Nazi scientists, Wiesenthal acted as the “deputy for the dead,” putting public pressure on world governments to bring war criminals to justice.

He was sometimes criticized for self-promotion and a love of the spotlight, but his efforts brought attention to the brutality of the past and held people accountable for their crimes.

According to several published accounts, Wiesenthal was asked in 1964 by another Holocaust survivor, who had become wealthy making jewelry, why he had continued his pursuit instead of trying to build a more normal life.

Wiesenthal responded: “You’re a religious man. You believe in God and life after death. I also believe. When we come to the other world and meet the millions of Jews who died in the camps and they ask us, What have you done?,’ there will be many answers. You will say, I became a jeweler.’ Another will say, I smuggled coffee and American cigarettes.’ Still another will say, I built houses,’ but I will say, I didn’t forget you.'”