If you want to understand Vladimir Putin’s stranglehold on power in Russia, watch the new film “Navalny,” which premieres Sunday at 9 p.m. ET on CNN.

Russia’s government has gone to great lengths to sideline the opposition leader Alexey Navalny, who was sentenced to prison after surviving a poisoning attempt.

The film documents the improbable detective work that identified the team of Russian spies who hunted and then tried to kill Navalny, as well as his recovery in Germany and return to Russia, where he was immediately arrested.

I talked to one of the investigators who unmasked the spies, Christo Grozev — who works with the investigative group Bellingcat — about his methods, his new mission documenting war crimes in Ukraine and his views about how the ethics of journalism must change to fight government corruption.

Our conversation, edited for length and clarity, is below:

WHAT MATTERS: In the documentary, you put all these pieces together — from telephone numbers to car registrations and so forth — to figure out who poisoned Navalny. How have you and Bellingcat developed this process of investigation? And what made you apply it to Russia in particular?

GROZEV: We started in a different way, by just piecing together social postings in the context of the initial Russian invasion of Ukraine in 2014.

The first investigation that Bellingcat did by just piecing together available pieces of data from the internet was the downing of (Malaysia Airlines) MH17 in July 2014.

At that time, a lot of public data was available on Russian soldiers, Russian spies, and so on and so forth — because they still hadn’t caught up with the times, so they kept a lot of digital traces, social media, posting selfies in front of weapons that shoot down airliners.

That’s where we kind of perfected the art of reconstructing a crime based on digital breadcrumbs. … But as time went by, sort of the bad actors that we were investigating, they started hiding their stuff better. … By 2016, it was no longer possible to find soldiers leaving status selfies on the internet because a new law had been passed in Russia, for example, banning the use of mobile phones by secret services and by soldiers.

So we had to develop a new way to get data on government crime. We found our way into this gray market of data in Russia, which is comprised of many, many gigabytes of leaked databases, car registration databases, passport databases.

Most of these are available for free, completely freely downloadable from torrent sites or from forums and the internet.

And for some of them, they’re more current. You actually can buy the data through a broker, so we decided that in cases when we have a strong enough hypothesis that a government has committed the crime, we should probably drop our ethical boundaries from using such data — as long as it is verifiable, as long as it is not coming from one source only but corroborated by at least two or three other sources of data.

That’s how we develop it. And the first big use case for this approach was the … poisoning of Sergei and Yulia Skripal in 2018 (in the United Kingdom), when we used this combination of open source and data bought from the gray market in Russia to piece together who exactly the two poisoners were. And that worked tremendously.

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