The latter study, however, did conclude that a tunnel may be at the location where Koper and Richter will now put their theory to the test.
"The train is not a needle in the haystack - if there is one, we will find it," Andrzej Gaik, the spokesman of the search committee, told AFP.
The committee consists of volunteers rather than of Polish officials who refrained from participating in the search efforts.
Gaik remains hopeful: "If we find a tunnel, then that is also a success. Maybe the train is hidden inside that tunnel."
The privately funded effort will be streamed live online and could be over within two days. Using special equipment, the search team is planning to drill three 100m holes into the ground.
ABOUT THE GOLD TRAIN
1 The story of a Nazi-era train with valuable art, gems and gold that disappeared at the end of World War II in 1945 has circulated for decades.
2 It is believed to have been last seen near the city of Wroclaw, which is today part of Poland.
3 Researchers and hunters have been unable to find the tunnel complex in which it is thought to be hidden.
4 The tunnel system carried the name "Giant" ("Riese"), which indicates the dimensions of the underground network.
5 The Riese tunnel network was originally also supposed to house a bunker for Adolf Hitler, but construction stalled as the Allied forces made gains.
The Polish news site Wiadomosci Walbrzyskie reported last year that up to 300 tonnes of gold could be hidden onboard the long-lost train, if it even exists.
Although such claims may turn out to be incorrect, some of the history of Nazi gold is well documented. Using jewellery from Jews and other prisoners who had been sent to concentration camps, the metal was melted into ingots. When the Allied forces advanced at the end of World War II, the Nazis transported that gold back to Germany amid fears that it might fall into Soviet hands. Experts say that not all of it has been found.
Researchers have remained wary of those claims, however. There is no evidence that the train has ever existed, although locals have passed on the story since 1945, when World War II ended.
Despite having refrained from participating in the search, local officials took the claims of the finding seriously at first. News agency Reuters quoted local official Marika Tokarska as saying last August: "Lawyers, the army, the police and the fire brigade are dealing with this. ... The area has never been excavated before, and we don't know what we might find".