Thousands marched through Moscow's central streets and those in St. Petersburg on Sunday to commemorate murdered Russian opposition leader Boris Nemtsov and voice criticism of authorities three weeks before a presidential election. Nemtsov, one of President Vladimir Putin's most vocal critics, was shot dead on February 27, 2015 as he walked across a bridge near the Kremlin. Aged 55, he had been working on a report examining Russia's role in the conflict in Ukraine. His killing sent a chill through opposition circles and initiated annual marches in Moscow that united different opposition parties and those who feel discontented about Russian authorities. A number of opposition politicians participated in the rally including Ksenia Sobchak, a contender for the March election where Putin is widely expected to win, and Russian opposition leader Alexei Navalny who has been barred from running in the election. According to a non-official organisation White Counter, which counts those who pass metal detector frames to take part in a rally, said Moscow's march gathered around 7,600 people.