Updated

Jailed former oil tycoon Mikhail Khodorkovsky on Friday marks 10 years since his arrest, which has become a key turning point in Russia's recent history.

The jailing of Khodorkovsky was widely seen as a punishment for challenging President Vladimir Putin's power. His arrest and the subsequent dismantling of his Yukos oil company sent a chilling signal to others and allowed Putin to consolidate his power and tighten state control over the nation's energy sector.

Khodorkovsky, once Russia's richest man, was arrested Oct. 25, 2003 when masked special forces stormed his plane on the tarmac of a Siberian airport. He was convicted of tax evasion and sentenced to eight years in prison.

In 2010, Khodorkovsky was handed a second prison term for stealing from his own Yukos oil company — the sentence interpreted by many as an instrument to keep him in jail until Putin won a third presidential term.

Khodorkovsky is set to be released in August 2014, and his partner Platon Lebedev, who was arrested a few months earlier, stands to walk free in May 2014. Their supporters fear, however, that investigators could be preparing yet another set of charges to keep them behind bars.

In May, a top liberal economist fled Russia saying he wanted to escape pressure from a new probe focusing on an independent report that was critical of the 2010 verdict. Investigators claimed that its authors had a conflict of interest because they had previously received money from Khodorkovsky.

Speaking to The Associated Press in New York City earlier this week, Khodorkovsky's son, Pavel Khodorkovsky, said his father tries not to focus on the prospect of being released: "He is not going to think about any possibility of his release and is not going to try and worry himself too much about what's coming next, because, as you can understand, for a person who has spent 10 years in jail, it's nerve-racking to try and always look forward to any particular date because that date has been changed in the past."

At the time of his arrest, Khodorkovsky was estimated to have a fortune of around $15 billion, making him Russia's richest person. During Putin's first term as president, Khodorkovsky challenged his power by funding opposition parties and was also believed to harbor personal political ambitions.

His actions defied an unwritten pact between Putin and top Russian tycoons, under which the government refrained from reviewing privatization deals that made them enormously rich in the years after the Soviet collapse on condition they don't meddle in politics.

While pressure mounted on Khodorkovsky in the months preceding his arrest, it still came as a shock for many, including himself.

Asked in an interview earlier this year what he would have done back then if he knew before his arrest that he would spend the next 10 years in prison, Khodorkovsky answered: "I'm afraid I would have shot myself. For me back then, my experience today would have been quite a shock."

Khodorkovsky's company, Russia's biggest oil firm at the time and a darling of portfolio investors, was sold off in pieces, with its most lucrative assets ending up in the hands of state-owned Rosneft.

Khodorkovsky's lawyer, Vadim Klyuvgant, described his arrest as a family tragedy that also has "broken lives of many people who worked in the company."

"It's obvious that it was the most important goal of his arrest or at least one of the most important goals: to break him, to make him do what they wanted him to do," Klyuvgant told the AP. "But they failed ... His spirit is not broken."