"We're better off than before we came," Zuroff said. "That doesn't guarantee Heim's capture, but I'm hopeful."
Zuroff launched the investigation last week in southern Chilean fishing town of Puerto Montt, where Heim's daughter long lived. Zuroff has said she frequently traveled to the Patagonian town of San Carlos de Bariloche in Argentina, which he visited this week.
"What we expected to do - and so far we have been successful - is to put in place the tools that will lead to his capture in the next few weeks - or at the most, months," Zuroff said while in Bariloche.
Heim was indicted in Germany after World War II on charges he murdered hundreds of inmates at the Mauthausen concentration camp in 1941. The Wiesenthal center says he injected the corrosive poison phenol directly into the hearts of many and used "other torturous killing methods."
Zuroff says that Heim's children have made no claim to a bank account with $1.6 million and other investments in Heim's name. To do that, they would have to produce proof that "Doctor Death" was dead.
A reward of 315,000 euros ($495,000) is being offered jointly by the center and the German and Austrian governments for information leading to his capture.
Heim tops the Wiesenthal Center's list of most-wanted Nazi war criminals.
The South American probe is part of the Jewish human rights organization's "Operation: Last Chance" - an effort to bring aging war criminals to justice before they die. If alive, Heim would be 94.
