Alexei Navalny, a leading Russian opposition politician, anti-corruption campaigner and preeminent critic of Russian President Vladimir Putin, has died in a Russian penal colony, according to a statement from prison service authorities.

Navalny had been poisoned by Russian agents in 2020, Western governments assessed. He was then imprisoned in connection with charges involving fraud, embezzlement and extremism, for which he denied any guilt.

“Those in power cannot hold it without the arrest of innocent people. They jail hundreds to instill fear in millions,” Navalny wrote, according to NPR last year.

The reported death of Navalny brings renewed scrutiny to the fate of government critics and dissenters in Putin’s Russia. The development comes roughly half a year after former Putin ally Yevgeny Prigozhin was reported dead in a plane crash two months after leading an armed rebellion that was described as the most serious threat to Putin’s authority in years.

In multiple documentaries over the past decade, FRONTLINE has examined Putin’s leadership and his government’s handling of dissent, with Putin’s critics noting that there’s been a high mortality rate for those who clash with the Kremlin.

Watch these six documentaries for insights into how Putin has handled domestic challenges to his authority in the past — and how the Kremlin’s crackdown on internal dissent, free speech and independent journalism has intensified amid Russia’s war on Ukraine.

Putin vs. the Press (2023)

This 2023 documentary chronicled the story of Nobel Peace Prize-winner Dmitry Muratov, a Russian journalist fighting to keep his newspaper alive and his reporters safe amid a government crackdown on free speech.

Putin’s Crisis (2023)

Released after the June 2023 armed rebellion led by Russian mercenary leader Yevgeny Prigozhin and his Wagner Group — and before Prigozhin’s death that August — this documentary examined domestic discontent around Putin’s troubled war in Ukraine, and how Putin responded.

Putin and the Presidents (2023)

This documentary, which examined Putin’s clashes with multiple American presidents as he’s tried to rebuild the Russian empire, also explored the Russian leader’s handling of dissent and criticism in his own country over the years.

Putin’s War at Home (2022)

In this film, FRONTLINE told the stories of some defiant Russian citizens risking arrest and imprisonment to push back against Putin’s crackdown on critics of the war in Ukraine.

Putin’s Revenge (2017)

In this two-part documentary, FRONTLINE examined how Putin consolidated his power at home, and then, U.S. intelligence officials believe, interfered with a U.S. presidential election.

Putin’s Way (2015)

This documentary probed the accusations of criminality and corruption that have surrounded Putin’s reign in Russia, and examined how he has wielded power.

This story was updated once more information became available.

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