A Moscow military court is beginning to hear the case of five people accused of involvement in the killing of opposition leader Boris Nemtsov.

Nemtsov was shot late at night in February 2015 as he and a companion walked across a bridge near the Kremlin. The brutality so close to the center of Russian power both frightened and angered supporters of the beleaguered opposition.

Five suspects, all of them Chechens, faced the court in Moscow on Monday as the hearings began. The suspected triggerman served as an officer in the security forces of the Moscow-backed Chechen leader, Ramzan Kadyrov.

The official probe has failed to identify those who ordered the killing, and Russian opposition activists have criticized the Kremlin for failing to track down the mastermind.