Tribute to Boris Nemtsov
Tributes and flags to slain Russian opposition politician Boris Nemtsov

Russians are marking the first anniversary of the murder of the leader of Putin's opposition with a memorial march through Moscow. Boris Nemtsov, a former deputy prime minister in Boris Yeltsin's government, was 55 when he was gunned down near the Kremlin on 27 Feburary last year, in what is believed to be a politically motivated killing.

At the time of his death, Nemtsov lead Russia's liberal political opposition to president Vladimir Putin. He was preparing to lead a march opposing Russia's attack on neighbouring Ukraine, when he was shot four times from behind by an unknown assailant on the Moskvoretsky Bridge.

The US ambassador to Russia, John Tefft, laid a wreath at Nemtsov's memorial, with a message reading: "From the American people".

Tefft told journalists that he had come to "honour the memory of a man who we knew as a government official, as a politician and, for many Americans, as a friend".

He added: "We are here today to honour his memory, the values for which he stood and to express our hope for the future that some of the dreams that Boris Nemtsov had will come true in Russia."

Nemtsov, who helped Russia's transition away from communism, was much disliked by Putin, and the lawyer for his family believes that Chechnya's leader Ramzan Kadyrov is implicated in his killing, perhaps even alongside the Kremlin itself.

Five Chechen men were quickly arrested following the shooting, and they face trial later this year as suspected killers working on contract.

Vadim Prokhorov says that the men have ties to Kadyrov's inner circle, and though the authorities have identified a minor interior ministry functionary as the man who organised the murder, his motive and funding are unclear. What's more, the man seems to have disappeared without trace.

The march through Moscow has been begrudgingly permitted to go ahead by the government, but Nemtsov's supporters are not allowed to march to the bridge where they have been keeping a shrine to him.