It has been eight decades since the start of the Great Terror that saw countless innocent victims across the Soviet Union executed or sent to the Gulag camps.
"It was an everyday case, so common for that period," political analyst Kolesnikov told AFP in his Moscow flat.
"My grandfather David Traub was caught up under the wheel of history."
It has been eight decades since the start of the Great Terror that saw countless innocent victims across the Soviet Union executed or sent to the Gulag camps -- and 25 years since the USSR itself finally ceased to exist.
But a fight over the historical truth -- and memory -- of the crimes of the Soviet regime still drags on in Russia as the current authorities under President Vladimir Putin stand accused of trying to minimise the dark chapters of the past in a bid to bolster their own grip on power.
Earlier this month leading human rights group Memorial -- which has been battling for decades to shine a light on Soviet abuses -- released a database with the names and some biographical details of around 40,000 people who served in the Stalin-era NKVD secret police from 1935-39.
Kolesnikov was able to find out more about the NKVD agent he had already tracked down in state archives as responsible for the 1938 arrest of his architect grandfather.
Some agents, it turned out, ended up being consumed by the very purges they had helped to conduct, arrested and executed along with their victims. Others went on to become decorated heroes in World War II.
"These people all had different fates," Kolesnikov, who works for the Carnegie Moscow Centre, said.
Kolesnikov's grandfather was accused of being a political opponent of the Bolsheviks -- his grandson guesses either to fulfil an arrest quota or due to a private vendetta. He died in the sick ward of his labour camp, leaving his wife and children.
"Unity" is the current buzzword among Russia's elite -- uttered repeatedly by Putin as he tries to forge a sense of national identity that instils loyalty to the Kremlin and smothers dissent.
The strongman leader -- and many of those who surround him -- served in the NKVD's successor organisation, the KGB, and headed its post-Soviet incarnation the FSB.
Central to their push is shaping a vision of the past that emphasises the USSR's victory in World War II and Stalin's role in achieving it while downplaying the Soviet crimes and repression.
When Memorial released its list of NKVD agents it provoked a level of interest -- both positive and negative -- that few at the organisation had expected.
In the first few days after the list was launched the website crashed as hundreds of thousands of people flooded on to search it.
"It turned out that for an awful lot of people it was terribly interesting -- for the descendants of victims and, however strange it might sound, for the descendants of those who worked in the NKVD," the group's board chairman Arseny Roginsky told AFP.
The veteran rights activist said that all these years after the repressions there was still an "empty space" in Russia's collective memory over the perpetrators.
"Our list of victims has millions of names but that never sparked such a discussion -- this one started a real public debate," he said.
From the Kremlin, however, the reaction was far from supportive.
Spokesman Dmitry Peskov warned that the issue was "very sensitive".
"There exist diametrically opposed points of view, and both of them sometimes have good arguments," he said.
Meanwhile, Memorial itself has been facing increasing official pressure as part of a broader crackdown on civil society.
In October it was blacklisted as a "foreign agent" under a controversial law that many have likened to the clampdown on Soviet-era dissidents.
There have been two major waves of soul-searching over Stalin's crimes in the country.
The first came under Soviet leader Nikita Khrushchev following Stalin's death in 1953 and the second under Mikhail Gorbachev and Boris Yeltsin as the Soviet Union crumbled and a chaotic Russia emerged in 1991.
Now under Putin, public attitudes seem to have swung in the opposite direction.
In a poll from the independent Levada centre earlier this year around 26 percent of people said Stalin's repressions could be justified, and almost 20 percent of those aged 18-24 had never heard of them.
While some steps towards keeping alive the memory of the repressions are still made -- such as the opening of a new Gulag museum in Moscow last year -- there are also controversial attempts to gloss over the past.
This month a restaurant called "NKVD" opened in the centre of Moscow -- creating a stir with its menus decorated with Stalin.
Shortly after its opening the neon sign was torn down.
Digging into the past is an important personal mission for descendants of Stalin's victims such as Kolesnikov.
He still has key questions about his grandfather's fate -- What was the real reason for his arrest? Why was he not released after his term finished?
His grandfather was posthumously rehabilitated under Khrushchev in 1955.
"It has been a long search already and once you start you want to get to the bottom of it," he said.
"It is important for the nation, for the history of the country. So we understand that we didn't only have victories, but that the repressions were a defeat," he said.
"The country needs to go through some repentance, some catharsis and then it will become a real nation."