Efraim Zuroff, the top official with the Wiesenthal Center, was quoted Thursday as saying Operation Last Chance would be a final push to locate elderly Nazis suspected of hiding in South America.
"The natural tendency is to be sympathetic toward people after they reach a certain age, but these are the last people on Earth who deserve sympathy," he told The Washington Post. "I think that in no way does the passage of time lessen their crimes."
The Wiesenthal Center is targeting its hunt at Aribert Heim, wanted for the deaths of hundreds of prisoners at the Mauthausen concentration camp in Austria from surgeries done with no anesthesia.
Investigators say they believe Heim is alive in Chile or Argentina despite claims by his family that he is dead.
German investigators said his family was entitled to more than $1.5 million left in a bank account if they offered proof of his death, which they have not done.
Zurroff said there is a $450,000 bounty for Heim.