Ezra Wolfinger / AP

A group of researchers have discovered a tunnel dug by Jewish prisoners to escape a concentration camp in the forests of Lithuania during the Holocaust.

With the help of ground-penetrating radar and other scanning techniques used in mineral and oil exploration, the group of American, Canadian, Israeli, and Lithuanian researchers were able to find the tunnel in the Ponar forest, just outside the capital of Vilnius. Their efforts did not disturb the remains of the more than 100,000 people buried there, 70,000 of whom were Jewish.

This discovery, announced Wednesday by the Israel Antiquities Authority, sheds new light on the 115-foot tunnel, which as The Times of Israel describes, 11 prisoners were able to use to escape the camp after 76 nights of digging using their hands, spoons, and other improvised tools.

As the Red Army advanced on Nazi-occupied Europe in 1943, German forces attempted to cover up evidence of their crimes, and brought 80 Jewish inmates from the nearby Stutthof concentration camp to burn bodies dumped in the forest.

During the months-long work, the prisoners, chained to one another, secretly dug the underground tunnel out of a pit they were kept in.

On the last night of Passover—April 14, 1944—forty prisoners escaped through the tunnel. Many were shot, but 11 reached partisan forces and survived.

But the tunnel had been lost in the years since World War II ended.

One of the lead researches on the excavation, Jon Seligman, an Israeli whose family has roots in Lithuania, said, “The discovery of the tunnel allows us to not only expose the horrors of the Holocaust, but also the hope for life.”

This discovery not only allows historians to retell this one aspect of the genocide by Nazi Germany, but is also an advancement in technologies is archeology. Richard Freund, one of the archaeologists on the team and a professor of Jewish History at the University of Hartford, said in a statement:

“This project represents the new frontier for the study of archaeology and the Holocaust and the integration with national histories. Geoscience will allow testimonies of survivors—like the account of the escape through the tunnel—and many events of the Holocaust to be researched and understood in new ways for generations to come.”

And with that technology, a tunnel that was as much as nine feet below the surface can be rediscovered more than 70 years later.

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