Story highlights Russia alleges that he ordered the murder of a Siberian town mayor in 1998

The former oil tycoon is one of Putin's biggest critics, calling for regime change

Khodorkovsky has already served 10 years in a Russian prison

(CNN) Russia has requested an international arrest warrant for former oil tycoon and Putin-critic Mikhail Khodorkovsky for the alleged murder of a Siberian town mayor.

Khodorkovsky, a loud detractor of President Putin, is wanted for allegedly ordering subordinates to kill the mayor of Nefteyugansk in 1998. Russia's Investigative Committee say he was attempting to avoid paying taxes for his oil company, Yukos.

Khodorkovsky has already served 10 years in jail after being convicted of fraud and tax evasion, a sentence he maintains was politically motivated. In 2013, he suddenly received a pardon from Putin

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On Wednesday, Russia's Director of the Investigative Committee Vladimir Markin said, "In the case of someone who has committed a serious crime, it is not important where the accused is hiding, whether it be in Russia and beyond its borders, even in the Antarctic. We are simply duty bound to take all legal measures to achieve his arrest."

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