In the last interview Boris Nemtsov gave, just hours before he was shot dead by unknown gunmen last Friday, he had accused Russian President Vladimir Putin of being a “pathological liar” on a radio show. The Russian opposition leader's death gained international attention and prompted thousands of supporters to mourn him on the streets of Moscow. 

Putin called the killing a “disgrace” and condemned the attack, but critics of his administration have claimed the involvement of the Russian government in Nemtsov's murder. Nemtsov, a vocal protester of Putin's government and policies, was a key organizer and speaker at massive rallies that erupted in December 2011, after a widespread voting fraud, ahead of Putin's inauguration as president for a third term.

“Putin is our expert in lying. He is a pathological liar,” Nemtsov reportedly told Ekho Moskvy, a local radio station, according to the Kyiv Post. “It is important to hold an honest election, with opposition parties naturally taking part, and to abolish censorship, in order to stop the propaganda of lies which turns the mentality of the Russian people upside down.”

Nemtsov also said, during the radio interview, that the presence of Russian troops in Ukraine was “well documented,” adding that the “main reason for the crisis is that Vladimir Putin started this insane policy of war with Ukraine, which is aggressive and murderous for our country and for too many of our citizens.

“We need political reform in this country. When all the political power is concentrated in the hands of one person and when that person rules eternally, it all ends with an absolute catastrophe,” he added, according to the Kyiv Post.

Earlier this week, Putin, responding to Nemtsov's killing, had reportedly said: “Russia should be made secure at last from the disgrace and tragedies of the kind we all experienced and witnessed just recently. I am referring to the daring killing of Boris Nemtsov in the very heart of our city.”

Nemtsov's comments came even as a fragile ceasefire, signed in Minsk, is currently active in eastern Ukraine. However, pro-Russian rebels have allegedly been fighting to gain control over the eastern city of Mariupol. As Western nations have continued to threaten Moscow with further sanctions, if the Ukraine truce failed, Nikolai Patrushev, the head of Russia's Security Council, accused the U.S. of plotting to oust Putin by financing opposition parties.