Efraim Zuroff, the Jerusalem office head of the Simon Wiesenthal Center, welcomed the five-year sentencing handed down to John Demjanjuk by a Munich court on Thursday.
Demjanjuk, 91, was found to have been an accessory to 28,060 murders at Sobibor camp in German-occupied Poland during 1943.
"We are very pleased that Demjanjuk finally has been convicted and sentenced to imprisonment," Zuroff said.
"This decision sends a very powerful message that even many years after the crimes of the Holocaust, the perpetrators can still be held accountable for their crimes," said the chief Nazi hunter, adding: "This is very, very important."
He expressed hope it would not be the last major war crimes trial in Germany.
"If anything it paves the way for additional trials in Germany," he said, adding a large number of aging ex-Nazis and their accomplices could still be tracked down and tried.
While welcoming the Demjanjuk sentencing, Zuroff made a point of condemning a decision by Bavaria to reject an extradition request for an alleged Dutch war criminal who lives in the district.
"We want to publicly express our sense of indignation at the outrageous decision by the Bavarian authorities yesterday to reject the European arrest warrant for Dutch convicted SS executioner Klaas Faber," he said.
The World Jewish Congress echoed the Weisenthal Center's sentiments, with its President Ronald S. Lauder saying there "must never be impunity or closure for those who were involved in mass murder and genocide, irrespective of their age”.
Lauder said that justice had been done with Demjanjuk's conviction, adding that the family members of those killed at the Sobibor death camp where the convicted Nazi criminal was a guard "will certainly welcome this verdict".
The WJC president praised Germany's efforts to continue prosecuting Nazi war criminals and their accomplices, and he urged other European countries "not to relent in their quest for bringing the perpetrators of the Holocaust to justice".
Lauder concluded, saying that the WJC will persist in it efforts to bring the "few old men out there who have the blood of innocent Shoah victims on their hands" before courts of law, to be tried and held accountable for their actions.
Yad Vashem chairman Avner Shalev issued a statement responding to Demjanjuk's sentence, reminding the public that the Germans would not have been as successful as they were in attempting to implement their "final solution" without the help of many Europeans and others. He added that there is "no statute of limitations for Nazi war crimes".
Shalev said that "although no court can bring back the lives of those murdered [at the hands of the Nazis]" the conviction of Demjanjuk has great moral significance, and is educational for future generations.
The Holocaust memorial museum chairmen made clear that the most important outcome of Demjanjuk's trial was that it increased international awareness of the Holocaust, showing that both society as well as individuals must be forced to assume culpability for the horrors that were perpetrated during the Holocaust.
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