MOSCOW -- Russians sympathetic to slain opposition politician Boris Nemtsov have honored the Kremlin foe 40 days after he was shot dead.
Several hundred people laid flowers on April 7 at the site of Nemtsov's slaying on a bridge just steps from the Kremlin.
Others took part in a "minute of nonsilence" arranged in advance on social network, standing still or honking their car horns at 11 a.m. Moscow time to send a message to the government that Nemtsov's killing will not be forgotten.
Nemtsov, a liberal former deputy prime minister, lawmaker, and regional governor who became a fierce critic of President Vladimir Putin and a vocal opponent of Russia's involvement in the conflict in eastern Ukraine, was killed on February 27.
In the Russian Orthodox tradition, relatives and friends honor the dead 40 days after their passing.
Nemtsov's slaying underscored the risks faced by Russians who challenge Putin's government.
Former allies, rights activists, and Kremlin critics say justice will not be done unless the person or people behind the killing are identified and brought to justice.
Many mourners said they had little hope that will happen.
"I’ve met here people like me who are also extremely worried about this loss, this foul murder, but who also don't know if the murderers will be punished or not," said Viktor Shchitkovsky, 65, a pensioner who had tears welling up in his eyes.
"I want to know who ordered this hit -- why they kill the truth and good people," he said.
One woman help aloft a placard reading, "Heroes don't die."
Opposition leaders Ilya Yashin, Aleksei Navalny, and Vladimir Ryzhkov were among those who paid their respects.
Ryzhkov told journalists that the opposition had agreed to formally appeal to Moscow City Hall to install a plaque honoring Nemtsov at the site of the killing, where a makeshift memorial has been repeatedly vandalized.
Others opposition activists had suggested demanding the bridge be renamed Nemtsov Bridge.
"I don’t insist on the bridge being renamed, but at the very least they need to establish some kind of memorial plaque," said Ivan Kaplan, 26, an architect. "That would be appropriate."
Five men from Russia's North Caucasus have been arrested on suspicion of involvement in Nemtsov’s slaying. They deny guilt.
The chief suspect, Zaur Dadayev, has said he initially confessed to involvement in order to win the freedom of an acquaintance, and a human rights activist who met with Dadayev in jail last month said there were signs he had been tortured.
Federal investigators have said a possible motive for Nemtsov's killing could have been anger over his position on the deadly Islamist militant attack in January on Charlie Hebdo, a French magazine that published caricatures of the Prophet Muhammad.
The Kremlin-backed head of the North Caucasus region of Chechnya, Ramzan Kadyrov, defended Dadayev in a statement posted on Instagram on March 8, calling him a "true patriot" and a deeply pious Muslim who was shocked by the cartoons.
Lawyers, allies of Nemtsov, and relatives of Dadayev have said they do not believe that anger over the Charlie Hebdo cartoons or Nemtsov's position on the issue was the motive in his killing.
As with past slayings of Kremlin critics, such as the 2006 killing of investigative journalist Anna Politkovskaya, many government opponents believe an honest investigation is unlikely because it would lead too close to the Kremlin.
Nemtsov's killing has sparked speculation of a deepening rift in Russia's ruling elite, pitting security agencies and powerful officials including Kadyrov against one another.
Putin has called the slaying a disgrace for Russia and told law enforcement organs last month that they should solve politically charged killings, which have harmed the country's reputation.
With reporting by RFE/RL's Russian Service