Man holds Ukrainian national flag during march to commemorate Kremlin critic Boris Nemtsov in central Moscow

A man holds a Ukrainian national flag during a march to commemorate Kremlin critic Boris Nemtsov, who was shot dead on Friday night, in central Moscow March 1, 2015. Opposition supporters march through Moscow on March 1 in memory of Nemtsov, whose murder has increased concern about Russia’s future among opponents of President Vladimir Putin. REUTERS/Sergei Karpukhin (RUSSIA – Tags: CRIME LAW POLITICS CIVIL UNREST)