A prominent Russian opposition leader faces his third investigation in five months as authorities intensify pressure on the opposition.The Investigative Committee said in a statement on Monday that they launched a new probe against Alexei Navalny, who was already charged with theft and with fraud and money laundering in two separate cases.Investigators now say they also suspect Navalny of defrauding the Union of the Right Forces, a now defunct liberal party, of 100 million rubles ($3.2 million) in 2007.Navalny, a charismatic 36-year-old lawyer, made his name exposing corruption in state-controlled companies. Last winter, he spearheaded a series of street rallies in Moscow that drew up to 100,000 people before March’s vote that handed Putin a third presidential term.In July, the lawyer was charged with the theft of half a million dollars from a state-owned timber company. Earlier this month, Navalny and his brother were charged with defrauding a transportation company of about $1.8 million.The opposition leader dismissed the accusations as politically motivated, and pointed to the fact that there was no injured party in either of the cases.Leonid Gozman, a former senior figure at the Union of the Right Forces, was quoted by the Interfax news agency, as denying reports of fraud at his party."This is another provocation, total nonsense,” he said.Navalny tweeted "that’s enough,” referring to the slew of criminal cases against him.