When Israeli archaeologist Yoram Haimi decided to investigate his family's unknown Holocaust history, he turned to the skill he knew best: He began to dig.

After learning that two of his uncles were murdered in the infamous Sobibor death camp, he embarked on a landmark excavation project that is shining new light on the workings of one of the most notorious Nazi killing machines, including pinpointing the location of the gas chambers where hundreds of thousands were killed.

Sobibor, in eastern Poland, marks perhaps the most vivid example of the "Final Solution," the Nazi plot to wipe out European Jewry. Unlike other camps that had at least a facade of being prison or labor camps, Sobibor and the neighboring camps Belzec and Treblinka were designed specifically for exterminating Jews. Victims were transported there in cattle cars and gassed to death almost immediately....