CNN  — 

When Russian opposition leader Alexey Navalny returned to Russia in 2021, there were many who feared he would face an untimely end. That became a reality on Friday with his death at a brutal Arctic Circle penal colony, where he had been incarcerated.

He was the most prominent voice of dissent in Vladimir Putin’s Russia, the lawyer, politician and corruption activist had for years orchestrated massive street protests and famously branded Putin’s United Russia party “the party of crooks and thieves.” Despite languishing in prison, he denounced the president over Russia’s invasion of Ukraine?and advocating anti-war demonstrations across the country.

The Kremlin has said it is investigating the critic’s death, the circumstances of which were not immediately clear.

What is known is that Navalny has joined the apparently ever-growing list of high-profile Russians who have died in mysterious circumstances. From plane crashes, accidental falls from windows to hangings, poisonings and health issues, the fates of some of those who dared to challenge the Kremlin are myriad.

Yevgeny Prigozhin

FILE PHOTO: The late Yevgeny Prigozhin, chief of Russian private mercenary group Wagner, then giving an address in camouflage and with a weapon in his hands in a desert area at an unknown location, in this still image taken from video possibly shot in Africa and published August 21, 2023. Courtesy PMC Wagner via Telegram via REUTERS/File Photo

Yevgeny Prigozhin, the bombastic mercenary boss – once one of the country’s most powerful oligarchs and a member of Putin’s trusted inner circle, died in 2023.

Speculation over Prigozhin’s eventual fate began soon after his march on?Russia?last summer.

The Wagner chief may have initially survived the aftermath of his failed insurrection, but many had?expressed doubts?over his future. After the aborted mutiny, the mercenary leader’s?plane mysteriously fell out of the sky?in August and he was subsequently?confirmed to have died?in the crash through genetic testing, Russian authorities said.

There is no concrete evidence that points to Kremlin involvement and, officially, the cause of the crash is unknown. Russian authorities have launched a criminal investigation.

Bill Browder, a Putin critic and the largest foreign investor in Russia before he was expelled from the country in?2005,?said in a post on X, formerly known as Twitter, that “Putin never forgives and never forgets.”

Boris Nemtsov

Russian opposition leader Boris Nemtsov was gunned down near the Kremlin on February 27, 2015. The killing took place two days before he was supposed to lead an opposition rally.

Boris Nemtsov, a vocal Kremlin critic who was a deputy prime minister in the late 1990s under President Boris Yeltsin, was?shot dead in February 2015?as he walked with his girlfriend in central Moscow.

A top official with the Republican Party of Russia/Party of People’s Freedom, a liberal opposition group, he had been arrested several times for speaking against Putin’s government.

After his death, opposition leader Ilya Yashin said his friend had been working on a report about Russian troops and their involvement in Ukraine.

In an interview with Newsweek magazine just hours before his death, Nemtsov said?Russia?was “drowning” under Putin’s leadership and was swiftly becoming a fascist state. “Due to the policy of Vladimir Putin, a country with unparalleled potential is sinking, an economy which accumulated untold currency reserves is collapsing,” he said.

Nemtsov’s death came two days before he was set to lead an opposition rally in the Russian capital. His killing took place within sight of the Kremlin. In 2017, five Chechen men were handed lengthy prison terms over his death. Many Nemtsov supporters suspected Putin’s administration of involvement.

Boris Berezovsky

Berezovsky leaves the High Court in London with his partner Yelena Gorbunova, left, in 2011.

Boris Berezovsky?was a colorful character and once powerful Russian businessman who fell out with the Kremlin and fled to England.

He had accumulated his wealth following the collapse of the Soviet Union, ditching his earlier career as a Moscow math professor and systems analyst for more lucrative enterprises. While a large chunk of his fortune came from the sale of luxury cars, his wealth and political influence skyrocketed when he bought into Russian media.

After losing favor with his government, he relocated to Britain where he began agitating against Putin, and even called for a coup to oust the Russian president.

Berezovsky was convicted of fraud and tax evasion in absentia by a Russian court in 2007. He also accused Russia of trying to assassinate him.

Berezovsky?was found dead on the bathroom floor of his UK home?in 2013 with a noose around his neck. British police said at the time that there were no signs of struggle and suggested the oligarch had taken his own life.

Alexander Perepilichnyy

Over the years, suggestions have emerged of the possible use of a rare plant poison in the death of Russian financier Alexander Perepilichnyy.

Alexander Perepilichnyy was a financier who provided evidence of alleged fraud against Russian tax officials. He died suddenly in 2012 aged 44 while jogging back to his home in Surrey, southwest of London.

It first appeared that the whistle-blower had died of natural causes.

But in 2015, plant toxicology experts from the Royal Botanic Gardens in Kew told a coroner’s court that traces of a rare plant poison – gelsemium – were found in his stomach. Two years later, there were?suggestions?that poison might have been slipped into sorrel soup, a popular Russian dish he had eaten shortly before his death.

However, police said later that they found no evidence that he was poisoned.

At the time of his death, Perepilichnyy was assisting in a case to uncover a multimillion dollar Russian money-laundering operation.

Sergei Magnitsky

A picture taken on December 7, 2012, shows  snow clad grave of Russian lawyer Sergei Magnitsky with his portrait on the tomb (C) at the Preobrazhenskoye cemetery in Moscow. The US Congress drew today a furious response from the Kremlin by passing legislation that targeted human rights abusers in the prison death of Magnitsky. Moscow immediately called the action "a theater of the absurd" and vowed to retaliate, turning what would have been a boost in trade relations between the two powers into another source of friction.  AFP PHOTO / ANDREY SMIRNOV        (Photo credit should read ANDREY SMIRNOV/AFP/Getty Images)

Russian lawyer?Sergei Magnitsky?died in a Russian prison in 2009.

He worked for Hermitage Capital, an investment firm run by American-born financier Bill Browder, and helped uncover a $230 million tax fraud and evidence that Russian government officials were involved in carrying it out, and then covering it up.

Soon after he made those revelations public in 2008, Magnitsky was arrested on separate tax fraud charges. He died a year later, while still in pre-trial detention. His family said crucial medical care was withheld, while a Russian presidential human rights commission report found evidence he had been beaten on the very day he died. The Russian government has always maintained that Magnitsky died of heart failure.

In the US, Browder launched a public campaign for justice, calling on Congress to introduce a law sanctioning individuals in Russia suspected of involvement in Magnitsky’s death and other human rights violations. The Magnitsky Act was passed by lawmakers in 2012.

Two weeks after the Magnitsky Act was passed, Moscow banned American adoptions of Russian children in apparent retaliation. Both measures are still in place.

Alexander Litvinenko

Alexander Litvinenko is pictured in a London hospital on November 20, 2006, three days before his death.

A British inquiry determined?Alexander Litvinenko, a former Russian agent turned Kremlin critic, had been poisoned at a London hotel bar in 2006 by two Russian agents who spiked his green tea with the highly radioactive polonium-210.

Litvinenko – who died a slow and painful death in the weeks following his poisoning – always asserted that Putin and the Kremlin were responsible for what had happened to him.

“You may succeed in silencing one man, but the howl of protest from around the world will reverberate, Mr. Putin, in your ears for the rest of your life,” he said in a deathbed statement.

The inquiry, led by judge Robert Owen, said that Putin “probably approved” the ex-spy’s killing.

The Kremlin has always denied the accusation and has refused to extradite the two agents accused of the poisoning to Britain.

Litvinenko had worked for the FSB, Russia’s successor agency to the KGB, the former Soviet secret police and intelligence agency. He specialized in tackling organized crime and his last job at the agency, after the collapse of the Soviet Union, was heading up its anti-corruption department – a position that made him many enemies.

After leaving the FSB, Litvinenko accused his former employers of orchestrating a series of apartment bombings in Russia in 1999 that left hundreds dead and led to Russia’s invasion of Chechnya later that year.

According to his widow, Marina Litvinenko, he had started working for Britain’s security services after he went to Britain as a whistleblower in 2000.

Anna Politkovskaya

A picture taken 17 March 2005 shows Russian human rights advocate, journalist and author Anna Politkovskaya during the book fair in Leipzig, eastern Germany, where she presented her book titled "In Putin's Russia". The Russian investigative journalist known for her critical coverage of the war in Chechnya was found murdered in Moscow 07 October 2006, Russian news agencies said. A neighbour found Politkovskaya shot dead in the hallway of the building where she lived in the centre of the Russian capital, a police official quoted by the agencies said. AFP PHOTO  / DDP / JENS SCHLUETER    - GERMANY OUT - (Photo credit should read JENS SCHLUETER/AFP/Getty Images)

A vocal critic of Russia’s war in Chechnya, she was gunned down in the entrance of her Moscow apartment in October 2006. In 2014,?a Moscow court sentenced five men to prison?for the killing.

Authorities alleged that an unidentified man asked Lom-Ali Gaitukayev, whom the jury found was a mastermind of the slaying, to kill Politkovskaya in exchange for $150,000 because of her reports of human rights violations and other issues, the Moscow city court said.

The New York-based Committee to Protect Journalists said her work chronicling human rights abuses in Chechnya led to threats against her and angered Russian authorities.

Shortly after her death, Putin denied any Kremlin involvement in her killing, saying that Politkovskaya’s “death in itself is more damaging to the current authorities both in Russia and the Chechen Republic … than her activities.”

Drownings, suicides and other unusual deaths

The list of deceased detractors who may have potentially fallen foul of the Kremlin could fill a book. On the same day Prigozhin was presumed to have been killed, RIA Novosti also reported the recent death of a former Russian security services general.

Gen. Gennady Lopyrev – who supposedly had knowledge of the construction of Putin’s Black Sea residence – was convicted of bribery offenses in 2017 and had been serving a sentence of 9 years and 8 months. According to RIA Novosti, while in custody he recently “suddenly fell ill” and?subsequently died in hospital on August 16. Lopyrev had always maintained his innocence of all charges.

Washington-based think tank Institute for the Study of War labeled Lopyrev’s death “suspicious” and said that its “insider source claimed Lopyrev was “the keeper of secrets” related to the construction of Putin’s residence in Gelendzhik, often referred to as “Putin’s Palace.”

In May, Russia’s Deputy Minister of Science and Higher Education,?Pyotr Kucherenko, 46, died while returning from a trip to Cuba, according to the ministry.

At least 13 high-profile Russian businessmen have reportedly died by suicide or in mysterious circumstances over the past year, six of them tied to Russia’s two largest energy companies, Gazprom and Lukoil. The latter took the rare public position last year of denouncing Russia’s war in Ukraine, and calling for the end of the conflict.

Russian sausage magnate-turned-lawmaker Pavel Antov died in India in December 2022 after falling from the third floor of his hotel, according to the Indian police. His friend and travel companion Vladimir Budanov died of a heart attack two days earlier, on Antov’s 65th birthday, according to the police. Budanov was 61 years old and had a preexisting heart condition, the police said, adding that they believed Antov’s death was a suicide.

Alexander Buzakov, the head of a major Russian shipyard that specializes in building non-nuclear submarines, also died suddenly in December 2022, Reuters news agency reported, with no cause of death given by the authorities.

Anatoly Gerashchenko, the former rector to the Moscow Aviation Institute, died in an unspecified accident months earlier, according to a statement from the institute.

Lukoil chairman?Ravil Maganov?also died in the same month after falling out of the window of a Moscow hospital, according to TASS. An initial statement from Lukoil had said Maganov “passed away following a severe illness.”

Alive but neutralized

Not all those who cross the Kremlin meet with an untimely end. But many are ultimately rendered unable to cause further problems for Putin and his government.

Navalny had been one such individual before his sudden death at a Siberian penal colony.

- Source: CNN " data-fave-thumbnails="{"big": { "uri": "https://media.cnn.com/api/v1/images/stellar/prod/240112204703-navalny-penal-colony.jpg?c=16x9&q=h_540,w_960,c_fill" }, "small": { "uri": "https://media.cnn.com/api/v1/images/stellar/prod/240112204703-navalny-penal-colony.jpg?c=16x9&q=h_540,w_960,c_fill" } }" data-vr-video="false" data-show-html=" Erin Burnett Out Front " data-byline-html="
" data-timestamp-html="" data-check-event-based-preview="" data-is-vertical-video-embed="false" data-network-id="" data-publish-date="2024-01-13T01:49:36Z" data-video-section="world" data-canonical-url="https://www.cnn.com/videos/world/2024/01/13/alexey-navalny-penal-colony-russia-pkg-chance-ebof-vpx.cnn" data-branding-key="" data-video-slug="alexey-navalny-penal-colony-russia-pkg-chance-ebof-vpx" data-first-publish-slug="alexey-navalny-penal-colony-russia-pkg-chance-ebof-vpx" data-video-tags="" data-details="">
navalny penal colony
What the life of Putin nemesis in Arctic penal colony looked like
02:36 - Source: CNN

Another Kremlin opponent who served time in prison was Mikhail Khodorkovsky. He was released in 2013 after Putin signed a decree pardoning the former oil magnate, who had been convicted of tax evasion and fraud.

Former Russian spy Sergei Skripal paid a heavy price for turning against the Kremlin. Skripal was convicted in Russia of spying for Britain before he was granted refuge in the UK after a high-profile spy swap in 2010 between the United States and Russia.

In 2018, he and his daughter Yulia were left in critical condition after being exposed to Novichok near their home in southern England.

They survived after a long stint in hospital, with Yulia revealing in the weeks after that their rehabilitation had been “slow and extremely painful.”

This is a developing story and will be updated

CNN’s Matthew Chance, Rob Picheta, Uliana Pavlova, Radina Gigova and Vasco Cotovio, Catherine E. Shoichet, Lynda Kinkade, Angela Dewan, Mariya Knight, Ivana Kottasova and Clare Sebastian contributed to this report.