Simon Wiesenthal always maintained that his motivation for six decades spent hunting Nazi war criminals was never anger.

"I am someone who seeks justice, not revenge," Wiesenthal declared. "My work is a warning to the murderers of tomorrow that they will never rest."

Wiesenthal spent almost 60 years hunting the leaders of the Holocaust and speaking out against neo-Nazism and racism before his death on Ttuesday. He said he wanted to remind the world that the Jewish experience was a lesson for humanity, as was his work seeking justice.

"Should history repeat itself, my example will repeat itself too... and not once, but 50-fold," he said.

Wiesenthal never imagined a high-profile life for himself. He was born on New Year's Eve, 1908, to Jewish merchants in a small town near Lviv, Ukraine. He studied civil engineering in Prague and Warsaw and later opened an architectural office.

His life changed when the Russians and the Germans occupied Lviv and the terror against Jews began. The Germans took Wiesenthal into custody in 1941 and sent him to a labour camp.

He passed through 12 concentration camps before he was liberated in the Mauthausen camp near Linz in Austria. When he was finally released, he weighed less than 100 pounds (45 kilos).

Wiesenthal said he began memorizing his captors' names during his detention. When he was freed, he decided to stay in Europe and took a job at the War Crimes Office of the U.S. army, where he helped prepare evidence against war criminals. It was the beginning of a mission that spanned a lifetime.

Though Wiesenthal had no training to help him, he was determined to hunt down the men who helped killed 89 of his relatives and about 6 million fellow Jews. He was able to nab the criminals by using and disbursing tips on former Nazis through a network of government agents, journalists and even other former Nazis.

"His greatest accomplishment was that he showed the world what one person determined to do the right thing can accomplish," said Rabbi Marvin Hier, founder of the Simon Wiesenthal Center in Los Angeles.

Wiesenthal was of course not without enemies, and he received threatening letters and phone calls throughout his life.

After a bomb was placed outside his Vienna home in 1982, a policeman always stood guard there and before his office. (German and Austrian neo-Nazis were later charged in the bombing, and one went to jail.)

Wiesenthal wrote numerous books and articles about his work, most notably his 1967 memoir The Murderers Among Us. That book became an HBO movie "Murderers Among Us: The Simon Wiesenthal Story," starring Ben Kingsley.

Wiesenthal was often asked why he took on the role he had instead of resuming a profitable career in architecture.

He gave one questioner this response: "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.' "

"Survival is a privilege which entails obligations,'' Wiesenthal wrote in his book Justice, Not Vengeance: Recollections.

Criticized once as a meddler by an Austrian justice minister, he freely acknowledged that no one had appointed him "the lawyer for six million dead people."

"No such appointment exists," he said. "But I've worked for over 20 years for the memory of these people, and I believe I've earned the right to speak for them."

Former German Chancellor Helmut Kohl said he was always impressed that Wiesenthal conducted his mission without venom but with dignity.

"What especially touched me was the fact that despite his personal experience, he never became bitter, and carried on in an admirable and just manner," Kohl said in a statement.

Wiesenthal was showered with awards for his work. But the one prize that always eluded him -- to his great disappointment -- was the Nobel Peace Prize.

Wiesenthal retired in April 2003, and told the Austrian magazine Format after his retirement: "My job is done… I found the mass murderers I was looking for. I survived them all.''