( CNN ) -- Former oil tycoon and Kremlin critic Mikhail Khodorkovsky arrived in Switzerland Sunday , according to a statement posted on his website . Khodorkovsky was pardoned and released from a Russian prison on December 20 after spending 10 years in jail after a fraud and tax evasion conviction . Less than a week after his release , Khodorkovsky was granted a Schengen visa -- which allows him to travel throughout the European Union -- by Swiss authorities . Khodorkovsky `` is grateful for the principled positions taken by the Swiss authorities over the many years of his unjust imprisonment , '' read the statement . `` Swiss judicial authorities were quick to recognise the politicised nature of Mr. Khodorkovsky 's prosecution . '' According to the statement , `` the purpose of his visit is a family matter , as he and his wife are accompanying their two sons back to school in Switzerland . '' Khodorkovsky has two twin sons studying in a Swiss school . Khodorkovsky and his wife traveled by train from Berlin , where they have been since Khodorkovsky 's release . After Russian President Vladimir Putin 's December pardon , the country 's Supreme Court will take a second look at cases against Khodorkovsky , state-run news agency RIA Novosti reported . The court cited the European Court of Human Rights ' criticism of the tax evasion and fraud case . The statement said Khodorkovsky has not made plans for permanent residency in Switzerland . Russia has faced international criticism for its treatment of Khodorkovsky , once Russia 's richest man , with countries including the United States accusing it of selective prosecution and abuse of the legal system . Khodorkovsky 's release was one of dozens , part of Putin 's new amnesty law that some critics have described as a public relations campaign ahead of the Winter Olympics in Sochi . In past statements to CNN , Khodorkovsky has said his prosecution was part of a Kremlin campaign to destroy him and take control of Yukos , the oil company he built from privatization deals of the 1990s . Khodorkovsky speaks out .
Former oil tycoon Mikhail Khodorkovsky arrives in Switzerland . Russian dissident travels to visit his family . Khodorkovsky was jailed for 10 years in Russian prison .