MOSCOW -- Slain Russian opposition politician Boris Nemtsov has been laid to rest following an emotional farewell ceremony attended by thousands of mourners.
Nemtsov, a vocal critic of President Vladimir Putin, was shot dead near the Kremlin on February 27, in the country's most shocking killing in years.
He was buried at Troyekurovskoye Cemetery on the outskirts of Moscow on March 3 after mourners streamed into the Sakharov Center, a prominent civil-rights organization, and piled flowers next to the open casket at a public memorial service.
"I am not saying goodbye because heroes never die," Dmitry Gudkov, one of a just a few opposition politicians left in parliament, said at the ceremony, which ended with a long line of mourners still waiting outside to pay their respects.
Black-and-white photos of the former deputy prime minister, whose career stretched from the promising days of growing democracy following the 1991 Soviet collapse to what Kremlin critics say is a clampdown on dissent under Putin, hung on a brick wall behind the coffin at the Sakharov Center.
Mourners in winter coats filed past, a few wiping away tears, in a public ritual that has followed the killings of several prominent Russians who have challenged Putin's government since he came to power 15 years ago.
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"Boris Nemtsov was one of the most prominent representatives of Russian intelligentsia and opposition. Now there's a gap in our ranks," homemaker Yelena Ustinova, 43, told RFE/RL outside the building.
"We lost a man who was able to consolidate people around himself -- people who were resisting the current regime of Putin," she said. "It's definitely a loss."
Mikhail Kasyanov, who was prime minister during Putin's first term and is now a vocal opponent, said at the service that Nemtsov "became an enemy for many people."
"He became an enemy because he spoke the truth, but many people don't want the truth," Kasyanov said.
"They don't like it -- not only do they dislike it, but many of them are ready to do what they have done -- they are ready for murder; for murder near the Kremlin walls, in the center of Moscow," he said.
"Such bright people, who live for the sake of their country, must not die," Mikhail Zadornov, an economist and banker who had known Nemtsov for 25 years, told RFE/RL outside the Sakharov Center after paying his respects.
"I am devastated," Konstantin Yankauskas, an associate of Nemtsov who was allowed to leave house arrest for the service, told RFE/RL. "Part of my internal world is falling apart now, with [the death of] Nemtsov. I am devastated."
"He was such a kind, good, and amazingly bright person," said Yankauskas, who is under investigation on what he says are false, politically motivated charges of election-law violations and fraud related to the funding of opposition leader Aleksei Navalny's campaign for Moscow mayor in 2013.
Opposition figure and anticorruption blogger Aleksey Navalny wrote on his blog site that Russian security forces acting on orders from President Putin were behind Nemtsov's murder though Navalny offered no evidence for this accusation.
PHOTO GALLERY: Russians Say Farewell
Russians Say Farewell To Boris Nemtsov
Politicians from Latvia and Poland said Russia officials had refused them entry to attend the funeral, including the speaker of Poland's Senate, Bogdan Borusewicz.
"I wanted to pay respect to the slain Boris Nemtsov and to all Russians who think like him," said Borusewicz, a key Solidarity dissident.
Latvian lawmaker Sandra Kalniete told AFP she was turned back at Moscow's Sheremetyevo Airport.
"I feel really proud to be labelled an enemy of Russia today. Russia in its current state does not have many friends," Kalniete said, adding that she had met Nemtsov on his visits to the European Parliament.
The ban prompted strong condemnation by the president of the European Parliament, Martin Schulz, who called it a "high affront," which will further set back relations with Moscow.
He said on March 3 that he will intervene with Russian authorities "in the strongest terms and demand an official explanation." Latvia holds the rotating EU presidency. The European Commission, Latvia, and Poland also joined the protest.
Among the most senior foreign officials scheduled to attend the funeral was Lithuanian Foreign Minister Linas Linkevicius.
U.S. Ambassador to Russia John Tefft also attended.
Among Russians, attendees included Yeltsin's widow, Naina; veteran Soviet dissident and rights activist Sergei Kovalyov, and tycoon-turned-politician Mikhail Prokhorov.
Russian President Vladimir Putin, who called the killing a "provocation" to destabilize the country, stayed away and sent his little-known representative in parliament, Garry Minkh.
Minkh said that "Boris loved Russia" and called his killing an "irreparable loss."
Navalny's request to be released from prison to attend Nemtsov's funeral was rejected by a Moscow court.
The Troyekorovskaya Cemetery is also the resting place of Anna Politkovskaya, an investigative journalist and Kremlin critic who was shot dead in Moscow in 2006.
The Sakharov Center has been branded a "foreign agent" under a law that Kremlin critics see as a part of a growing campiagn to silence dissent during Putin's third term.
It has come under pressure in the past from the authorities and from pro-government activists.
Ukrainian Connection
The woman who was with Nemtsov when he was killed said she has been questioned extensively by authorities and told them everything she knew, butdid not see the gunman who pulled the trigger.
Anna Durytska, a 23-year-old Ukrainian model, was allowed to leave Russia and fly home late on March 2.
Federal Investigative Committee spokesman Vladmir Markin said on March 3 that Durytska had signed a document barring her from disclosing "any information related to the preliminary investigation."
Markin said investogators were pursuing "all lines of inquiry in this case -- witnesses are being questioned, videos from the CCTV cameras have already been examined, some material evidence has been taken."
The Investigative Committee said earlier that it was looking into several possible links for Nemtsov's slaying, including an attempt to destabilize the state, Islamic extremism, the Ukraine conflict, and his personal life.
Many opponents of Putin hold the Russian leader responsible for creating an atmosphere that encouraged the crime by fanning nationalist, anti-Western sentiments and vilifying the opposition.
Putin and his government have sought to deflect blame, calling the killing a "provocation" and suggesting Kremlin opponents could have been behind it.
Russian Foreign Minister Sergei Lavrov said on March 2 that Nemtsov's murder should not be used for "political purposes."
He told the UN Human Rights Council in Geneva that Putin had "immediately handed down all instructions and is ensuring special control over this investigation."
Tens of thousands of supporters marched through central Moscow on March 1 in a silent tribute to Nemtsov.
Hours before he was killed, Nemtsov gave a radio interview in which he had slammed Putin's "mad, aggressive policy" on Ukraine, where Russian-backed rebels have seized territory and are fighting government forces in a conflict that has killed more than 6,000 people since April.
Ukranian President Petro Poroshenko signed a decree on March 3 posthumously decorating Nemtsov with the Order of Liberty, a high state medal.
"Boris will remain a friend of Ukraine and a patriot of Russia," Poroshenko said on his website, adding that Nemstov had shown that it is possible to be both.
Pro-Kremlin newspaper Izvestia reported on March 3 that investigators were "focusing on" on the possibility that Nemtsov's killing was connected to the conflict in Ukraine.
Citing unnamed sources, Izvestia said investigators "are not ruling out that Nemtsov was killed on the orders of the Ukrainian special services" and that "the organizers of the crime could have been Chechen militants" who have fought alongside government forces against Russian-backed separatists in the war.
WATCH: Mourners File Past Boris Nemtsov's Coffin
Echoed by other Western officials, U.S. Secretary of State John Kerry has called for Russia to conduct a prompt, thorough, transparent, and credible investigation into the slaying.
White House spokesman Josh Earnest on March 2 described Nemtsov as a "tireless advocate for his country, an opponent of corruption, and an advocate for human rights and greater transparency."
Tens of thousands of supporters marched through central Moscow on March 1 in a silent tribute to Nemtsov.
U.S. President Barack Obama said Nemtsov's killing reflected a climate "inside of Russia in which civil society, independent journalists, people trying to communicate on the Internet, have felt increasingly threatened" and constrained.
Asked in an interview with Reuters news agency on March 2 whether he believes Putin's government was involved, Obama said he had "no idea at this point exactly what happened."
But he said that "freedom of the press, freedom of assembly, freedom of information, basic civil rights and civil liberties inside of Russia are in much worse shape now than they were four or five, 10 years ago."
Obama said that "increasingly the only information that the Russian public is able to get is through state-controlled media outlets. That is a problem. It's part of what has allowed, I think, Russia to engage in the sort of aggression that it is has against Ukraine."
The Russian newspaper Kommersant on March 2 quoted anonymous sources in the Interior Ministry as saying there was no closed-circuit TV video of the killing because the cameras in question were not working at the time.
However, Yelena Novikova, a spokeswoman for Moscow's information-technology department, which oversees the city's surveillance cameras, said cameras "belonging to the city" were operating properly when Nemtsov was killed.
She told the AP news agency that federal authorities also had surveillance cameras near the Kremlin that are not under her organization's control.
Novikova would not confirm the existence of any video of the killing, saying the police investigation was still under way.
