MOSCOW (AFP) - Thousands marched through central Moscow on Sunday in memory of opposition leader Boris Nemtsov ahead of the second anniversary of his murder.
The 55-year-old former deputy prime minister was gunned down near the Kremlin on February 27, 2015. He was the highest-profile killing of a critic of President Vladimir Putin since the ex-KGB officer took charge in 2000.
Five Chechen men from Russia's volatile North Caucasus are on trial for carrying out a contract hit, but those who ordered the killing have not been brought to justice.
"We came to pay tribute to the honesty and bravery of Boris Nemtsov," pensioner Galina Zolina told AFP, clutching a bunch of red carnations.
"We want to show the authorities that we haven't forgotten." Nemtsov, a charismatic figure who went from Kremlin insider under Boris Yeltsin to one of Putin's fiercest foes, was shot four times in the back as he walked home across a bridge with his girlfriend.
Sunday's march was permitted by the authorities but was not allowed to go past a makeshift memorial officials have repeatedly sought to dismantle at the spot where he was killed.
Some 15,000 demonstrators, according to an estimate by the organisers and AFP, took part.
Heavily escorted by police, they waved Russian flags and posters criticising the Kremlin and Russia's intervention in Ukraine, which Nemtsov had opposed right up to his death.
In one incident, an unidentified assailant threw what appeared to be a green antiseptic at former prime minister Mikhail Kasyanov, current chairman of the opposition People's Freedom Party. Kasyanov, his face covered in blobs of green liquid, stayed in his position on the front line of the march.
"The march can maybe get the attention of the authorities," said unemployed biologist Alexei Kuznetsov.
"It might be able to influence the investigation, show that the case resonates in society even if the authorities try to ignore it." In the northwestern city of St. Petersburg, some 1,800 people also marched in memory of Nemtsov, brandishing signs that read "Who is the mastermind?" "Nemtsov was a true leader," said Andrei Pivovarov, local leader of opposition Open Russia. "If he were alive, Russia would have been different." .
Last October five men - including a member of an elite interior ministry unit in Chechnya - went on trial in a military court in Moscow for carrying out the contract killing for 15 million rubles (currently $250,000, 240,000 euros).
But despite claims from officials that the case has been solved, Nemtsov's family and allies insist that the probe into his death has left the masterminds untouched.
They say he was killed to stop his political activities - a murder trail that purportedly leads to the inner circle of Ramzan Kadyrov, Chechnya's Kremlin-loyal strongman.
"The investigation stopped at the level of those who carried out the murder but nothing has been done to find those who ordered it," said Vadim Prokhorov, the lawyer for Nemtsov's family.
Nemtsov's slaying sent a chill through Russia's marginalised opposition.
The march came as authorities released prominent activist Ildar Dadin from jail in Siberia.
Dadin, who spent 15 months behind bars, was the only person to be convicted under a controversial law against public protests that has helped snuff out demonstrations against the Kremlin.