Minutes after a judge in Croatia condemned Dinko Sakic in 1999 to 20 years in prison for crimes committed during World War II, a man came up to Efraim Zuroff and told him he only had two words for him: ``Thank You.''

Zuroff, 61, a Nazi hunter from the Simon Wiesenthal Center, had captured Sakic in Argentina, where the head of Jasenovac, the largest Jewish extermination camp in Croatia, had been living for years.

The man who approached Zuroff in court was the brother of Milan Boskovic, whom Sakic was believed to have executed with his own hands.

``That was one of the happiest moments of my career,'' Zuroff said during a three-day visit to Miami to promote his book Operation Last Chance, which chronicles his quest to bring Nazi criminals to justice during three decades.

Zuroff appeared Monday night at Florida International University. He will also speak at 7:30 p.m. Tuesday at The Shul of Bal Harbor at 9540 Collins Ave., Surfside, where he will sign copies of his book.

Zuroff, the last of a small legion of men who hunted down Nazis through five continents, is working against the clock, well aware that almost seven decades since the Holocaust, few Nazis remain alive.

That's why in 2002, Zuroff launched an offensive called Operation Last Chance, which offers financial rewards up to $10,000 for information that leads to the conviction and punishment of Nazi war criminals. The project has led to the names of 520 suspected Nazi officials, 100 of which have been submitted to local prosecutors.

``Finding them is not difficult,'' said Zuroff, who leads the Wiesenthal Center in Jerusalem. ``The biggest obstacle we face is the lack of political will by certain governments to either investigate or prosecute these cases.''

Zuroff began his career as a Nazi-hunter in 1980, when he was hired by the U.S. Justice Department's Office of Special Investigations to be its sole researcher in Israel. Later, while at the Wiesenthal Center, he worked to get Canada, Australia and Great Britain to pass laws that allow the prosecution of Nazi criminals in those countries.

One of the most frustrating setbacks of Zuroff's career occurred last summer, he said.

For more than two years, he had been following leads on the whereabouts of Aribert Heim -- an Austrian doctor nicknamed ``Dr. Death'' because he removed the organs of Jewish prisoners without using anesthesia. The Wiesenthal Center offered a $500,000 reward for Heim's capture.

But relatives of Heim's and other witnesses told The New York Times that in 1992, he had died of rectal cancer in Cairo, where he had lived and converted to Islam -- and also changed his name to Tarek Hussein Farid.

German police confirmed that a suitcase found at the Hotel Kasr el-Madina, in Cairo, where Heim lived, contained letters and legal and financial records that linked Heim to the suitcase.

Zuroff refuses to close the case because he doubts any information provided by relatives of Nazi officials.

``I want to convey the message that that the passage of time in no way diminishes the guilt of the killers,'' Zuroff said of former Nazi officials.

``The victims of the shoah deserve that an effort be made to bring the killers to justice. This is what we owe the victims.''