KYIV -- A former Russian lawmaker who defected to Ukraine and aired damning criticism of Russia's leadership has been gunned down in broad daylight in the heart of Kyiv in what Ukraine's president called "an act of state terrorism by Russia."
A city police spokesman told RFE/RL that ex-Duma Deputy Denis Voronenkov was killed by a gunman as he and his bodyguard were approaching the five-star Premier Palace Hotel on March 23.
An Interior Ministry spokesman at the scene, Artem Shevchenko, said the attacker fired at least eight shots at the 45-year-old Voronenkov with an "old Soviet pistol." He said the incident was caught on security cameras.
The attacker was shot in the ensuing gunbattle with Voronenkov's lone bodyguard and apprehended by police on the street nearby. He later died in hospital, officials said, but there was initially no word on his identity.
The Interior Ministry spokesman said the bodyguard, who was wounded in the exchange of gunfire with the assailant, was provided by Ukrainian authorities in the past month because there was "reason to fear" that Voronenkov's life might be in danger.
Kyiv police are in charge of the investigation, the Interior Ministry said, and it is being classified as an "assassination."
A Kremlin spokesman quickly dismissed speculation of Russia's involvement as "absurd."
Frants Klintsevich, deputy head of the Defense and Security Committee in the Federation Council, Russia's upper house of parliament, told Russia's state-run Rossiya-24 TV that he thinks Voronenkov's killing was likely "an act of provocation" by the Ukrainian Security Service (SBU).
Since he fled Russia in October, Voronenkov had become a vocal critic of Kremlin policy toward Ukraine, including its military invasion and annexation of Crimea. But the former Communist lawmaker was also unpopular among Ukrainian nationalists, some of whom were dubious of his loyalties and critical of authorities fast-tracking a Ukrainian passport for Voronenkov.
In an exclusive interview with RFE/RL last month, Voronenkov compared present-day Russia to Nazi Germany, called the seizure of Crimea "illegal," and said he had been "hounded" into exile.
Ukrainian President Petro Poroshenko said in a statement after the March 23 shooting that Voronenkov had been "forced to leave" Russia "for political reasons." He added, in a reference to Moscow's interference in Ukraine since the ouster of pro-Moscow Ukrainian President Viktor Yanukovych in early 2014, "Voronenkov was one of the main witnesses of the Russian aggression against Ukraine and, in particular, the role of Yanukovych regarding the deployment of Russian troops to Ukraine."
WATCH: 'I Won't Hide,' -- Voronenkov Said, One Month Before Assassination
Poroshenko's statement did not offer any evidence of Russian involvement.
Ukrainian Prosecutor-General Yuriy Lutsenko called the assassination a "typical public Kremlin punishment of a witness" but also provided no details.
"We believe that all the falsehoods that can already be heard about much-hyped Russian involvement are absurd," Dmitry Peskov, a spokesman for Russian President Vladimir Putin, was quoted by Reuters as saying as word spread of the killing in Kyiv.
"We hope that the killer and those behind the murder will be exposed," Peskov said, according to TASS.
Peskov also repeated a frequent criticism of Moscow's against Kyiv since fighting broke out in eastern Ukraine in early 2014, saying Ukrainian authorities proved unable to protect Voronenkov.
Interior Ministry spokesman Shevchenko told RFE/RL that "absolutely the beneficiary of the murder is Russia" but stressed that investigators were exploring all possibilities.
Voronenkov was a Communist Party deputy in the State Duma, Russia's lower house of parliament, from 2011 until an election in September 2016.
Voronenkov and his wife, Maria Maksakova, a renowned opera singer and also a former Russian legislator, told RFE/RL in February of leaving Moscow for Kyiv after Russian investigators called for a probe into allegations he was involved in the illegal seizure of property in Moscow.
In the interview, Voronenkov compared present-day Russia to Nazi Germany, saying that Russia's Federal Security Service (FSB) controls everything in the country.
He was also highly critical of Russia's 2014 annexation of Ukraine's Crimea peninsula, calling it "a mistake" and "illegal" despite the fact that he was registered as having voted for it. In February, he claimed he was not present in parliament the day of the vote and that another legislator used his voting card.
While in Ukraine, Voronenkov said he had testified against former Ukrainian President Yanukovych, who is suspected of corruption and of ordering the killing of more than 100 people during pro-EU protests in Kyiv that led to his ouster in February 2014.
Voronenkov and Maksakova told RFE/RL last month they were renting an apartment in Kyiv and that they feared for their safety after speaking out against Moscow.
"We need to be careful. We are poking a sore spot of the Kremlin with our statements," Voronenkov said.
Shevchenko described the shooting, at around 11:30 a.m. at the busy intersection of Taras Shevchenko Boulevard and Pushkinska Street, as brazen.
Ilya Ponomarev, another former Russian lawmaker who defected to the West and the only Duma deputy to have voted against Crimea's annexation, said in a post on Facebook that Voronenkov was on his way to meet him when he was shot. But that information has not been confirmed.
"There are no words," Ponomarev wrote, adding the scenario seemed an "obvious" one to him.
"I said [before] that Voronenkov is not a crook but an investigator, deadly dangerous for Russian law-enforcement officers. My deepest condolences to Maria Maksakova," he said.
The killing could have far-reaching consequences for Ukraine, which is locked in a three-year conflict with Russia-backed militants in its eastern regions that has cost the lives of more than 9,900 people.
Volodymyr Ariev, a Ukrainian lawmaker from Poroshenko's ruling party, on Twitter likened the murder to a "new Litvinenko case," a reference to the former-Russian-spy-turned-British-operative who fled Moscow for London and was murdered in 2006. The assassination by radioactive poisoning was "probably" approved by President Vladimir Putin, a U.K. inquiry found last year.