That same month, a construction crew building a new office complex in western Ukraine burrowed into the corpses of several dozen more Jews.
Stumbling upon such mass graves is not particularly unusual in Eastern Europe.
Less well known is how many more "martyr sites" lie undiscovered and unmarked in fields and forests across the region -- wherever mobile Nazi killing units scorched the earth in the so-called "Holocaust of bullets."
It seems momentum is growing in the search for such sites.
French Catholic priest Patrick Desbois has pinpointed 600 in Ukraine over the past seven years, and says he may find another 1,800 as he moves farther east.
The Killing Sites Project of the Yad Vashem Holocaust Memorial in Jerusalem has identified from archives some 700 settlements in Ukraine and 200 in Belarus where Jews likely were massacred.
Even on Polish soil, where it seems every aspect of the six Nazi death camps has been dissected and detailed, the country's chief rabbi says evidence is mounting that a number of unmarked mass graves remain in the country's eastern woodlands.
"From time to time we'd hear about them," Rabbi Michael Schudrich said. "But over the past two to three years, more have come forward.... You begin to realize we may be talking about a much larger number than anyone was talking about previously."
Marking and memorializing these killing fields makes for far more than a historical footnote. Research may one day alter the 6 million figure of Jewish victims of the Holocaust, as recently opened archives in Eastern Europe enable researchers to fill in the blanks of what had been a virtual black hole in Holocaust research: the genocide of Jews in the Soviet Union.
With archival materials and witness testimonies casting a spotlight on what today is Ukraine, Belarus, Moldova, eastern Romania and western Russia, scholars soon may be able to record a more accurate death toll from the Holocaust.
Those who still lie buried in unmarked pits may help elucidate.
The primary problem in finding the mass graves is the nature of the killings themselves, which began well before the first gas chamber was operational in Poland in 1942.
When Nazi forces invaded the Soviet Union in July 1941, paramilitary units called Einsatzgruppen, or "special-duty groups," trailed behind, systematically cleansing the countryside of Hitler's "Jewish-Bolshevik" enemies.
The most notorious event occurred at Babi Yar, a ravine in Kiev where nearly 34,000 Jews were shot over two days in September 1941.
The Einsatzgruppen's own records claim responsibility for 1 million deaths; historian Raul Hilberg puts the figure at 1.4 million.
After the Holocaust, relatives who might have memorialized these killing sites were dead themselves or had fled elsewhere.
Then, as the Iron Curtain came down on Eastern Europe, the Soviet Union -- which had lost 20 million of its own citizens during the war -- ordered that no one ethnic or religious group be singled out for its victimization. Instead the carnage was portrayed as an ideological battle between communism and fascism.
This helps explain why the memorials the Soviets did build often were labeled generically for "Soviet victims of fascism."
After Stalin launched his anti-Zionist crusade in the early 1950s, the topic of Jewish victimhood became taboo and those probing it ran the risk of imprisonment.
Nevertheless, members of the Extraordinary Soviet Commission to Investigate the Crimes of the Nazi Occupiers were quite meticulous in documenting the Nazis' vast crimes, Western researchers say, and their evidence was used in court to convict alleged collaborators.
Yet while Germany became a treasure trove for Holocaust research, the Soviet Union remained closed.
Only in recent years have researchers begun to reveal the stories Soviet archives have to tell.
"Political developments in the past 20 years have enabled us to focus on an area of the Holocaust that may not have been prioritized enough," said Philip Carmel, international relations director for the Brussels-based Conference of European Rabbis, which is pursuing an ambitious project of its own to document the Jewish cemeteries of Europe.
One of the more critical breakthroughs in researching the unmarked graves came when the vast Soviet archives on the subject were copied and transferred to the U.S. Holocaust Memorial Museum. When cross-referenced with other sources for reliability, these once-sealed archives illuminate a trail for researchers to follow and unravel the mystery of missing bodies.
A windfall of material also came from the International Tracing Service's secret Holocaust archive at Bad Arolsen, Germany, which recently transferred its millions of images of concentration camp survivors to the museum in Washington.
Buffered by this research, the mass graves movement appears to be gathering speed.
Desbois soldiers on with his small but methodical project. Schudrich says the Polish Jewish community soon will be reaching out to non-Jewish Poles to help locate the last remaining mass graves.
The director of Yad Vashem's Killing Sites project, David Bankier, says he and his colleagues plan to start field research next year in Ukraine.
"Why is this important? It's important for the Jews who live in these countries," said Bankier, who heads Yad Vashem's International Institute of Holocaust Research. "They would like to have a gravestone on the site where their family members were assassinated. And these are the only cemeteries for them."
But even if these graves are discovered and marked, what next?
With few or no Jews remaining in these areas to preserve and protect them, untended sites may become vandalism or looting targets.
Some marked sites already have been spotted with bits of bone lying about. Experts suspect looters went excavating for gold, jewels and other valuables.
Marking these sites "kind of identifies for them where to dig, so rather than be helpful, it does the reverse," said Rabbi Andrew Baker, director of international Jewish affairs for the American Jewish Committee.
"If you create a memorial, have a ceremony, then go back to Israel or the United States, the concern is what happens to that site. You haven't completed the task."