One bullet, one Jew.

When Father Patrick Desbois heard that chilling Nazi maxim, he knew that he had to make a journey into one of the darkest corners of the Holocaust.

After a five-year investigation he had received a shocking insight into the mechanics of genocide — and strong indications that historians may have to raise their estimate of how many Jews were killed.

Working with a ballistics expert, the 53-year-old French priest dug up the mass graves of Ukraine.

"Every village was a crime scene,” he says, “and each case was different because the heads of the killing squads had to take in all the different factors — the geography, the transport available, the proximity of partisans — before organising the most efficient massacre.”

As his work in the Nazi killing fields continues, he is convinced that the figure for the number of Jewish dead will have to be revised upwards.

“Surely at the end of it all the numbers will be larger,” Father Desbois said, “but we are still inspecting sites in Belarus and there is the vastness of Russia ahead of us.”

At present, Paul Shapiro, of the US Holocaust Memorial Museum — which has been co-operating in Father Desbois’s body hunt — reckons that 1.5 million Jews were murdered by the Germans, their allies and collaborators in the towns and villages of Ukraine, Belarus, Russia and other former Soviet republics.

As Hitler’s armies pressed into Russia, the Einsatzgruppen — Operational Groups — rounded up the Jews, forced them to dig pits, strip and lie in the mud until they were shot.

Hundreds and thousands were killed even before German bureaucrats met in 1942 at the Wannsee Conference to work out the logistics of systematically murdering European Jewry and before the concentration camps were slaughtering their inmates. Father Desbois calls it “the Holocaust by bullets”.

Click here to read the full report from the London Times.