Mikhail Khodorkovsky, once the richest man in Russia, is back on trial in Moscow. The fallen oligarch, who’s already serving a sentence for tax evasion, has been charged with stealing oil and could face an additional 22-year sentence. Observers say the trial is a farce.Mikhail Khodorkovsky once ran Russia's biggest oil company. He used part of his fortune to fund Russian opposition parties and publicly criticized Vladimir Putin, who was Russian president at the time. Khodorkovsky paid a high price for those activities. The government seized his oil company and convicted him of tax evasion. He has been imprisoned since 2003. That has him a symbol for Russian opposition groups, who see him as a political prisoner. They say the new trial is designed to keep Khodorkovsky in jail for the rest of his life.