As the head of Yukos oil and valued at $15 billion, Khodorkovsky was once Russia's richest man. He benefitted from the country's privatization of state assets in the 1990s.
In October 2003 Khodorkovsky was arrested and later convicted of tax evasion. He and his business partner, Platon Lebedev, were sentenced to eight years in prison. Khodorkovsky had refused to heed warnings from President Vladimir Putin that oligarchs were to avoid politics, and his imprisonment was widely viewed as politically motivated.
In 2010, just a year before he was scheduled to be released, Khodorkovsky was convicted and sentenced to a second prison term for money laundering and embezzlement. He is set to be released in August 2014.