Hours after exiled Russian lawmaker Denis Voronenkov was shot dead Thursday outside an upscale hotel in Kiev, the man he was en route to meet said Voronenkov knew about illegal smuggling and money laundering operations run by members of Russia’s ruling class.

Voronenkov, 45, was gunned down on a busy street in a daylight shoutout that police say left his killer dead and his bodyguard wounded. Voronenkov, a former member of Russia’s State Duma who renounced his Russian citizenship after fleeing to Ukraine in late 2016, was on his his way to meet with Ilya Ponomarev, another exiled Russian lawmaker and a prominent Kremlin critic.

Ukrainian President Petro Poroshenko called the assassination an act of Russian “state terrorism” on Thursday, but Russian officials have denied any involvement.

Get Breaking News Delivered to Your Inbox

In a phone call with CBS News, Ponomarev also accused his home country’s government of killing Voronenkov -- to send a message.

“I think the prime motivation was to show to others in Russia that everybody who would switch sides and would go to support Ukraine would be punished,” Ponomarev said.

In this photo taken on Monday, Feb. 27, 2017, Denis Voronenkov visits a movie theater in Kiev, Ukraine. Ukrainian police said Voronenkov was shot dead Thursday by an unidentified gunman at the entrance of an upscale hotel in the Ukrainian capital. AP

Throughout much of his career, Voronenkov was known as a loyal proponent of the Kremlin, but in the months since he left -- claiming persecution at the hands of Russian security agencies -- he became an outspoken critic.

Voronenkov and Ponomarev each testified to Ukrainian investigators as part of that country’s treason investigation into former president Viktor Yanukovych, an ally of Russian President Vladimir Putin who was ousted following massive protests in February 2014. The duo had been expected to testify again on Thursday.

Ponomarev said he believes Voronenkov’s plan to open an investigative agency in Ukraine may have crossed the line.

“He was an ex-minister of security forces in Russia, and he was one of the lead investigators... he knew a lot of misdeeds of Russian elites,” Ponomarev said, referring to Voronenkov’s time working for the Federal Drug Control Service of Russia. “He had firsthand knowledge of their participation in illegal smuggling activities and money laundering. He had knowledge of their finances.”

As a member of the Russian legislature’s national security committee until he left the country in October 2016, Voronenkov had years of access to closely guarded state secrets.

Ponomarev said Voronenkov planned to “work closely with Ukrainian investigators.”

Ponomarev fled Russia in 2014 after being the lone member of the legistlature, or Duma, to vote against Russia’s annexation of Ukraine’s Crimean peninsula.

Ukrainian forces remain at war with Russian-backed separatists in the eastern part of the country, and the two neighbors engaged in a new battle in their long-running rhetorical war Thursday after the assassination.

Poroshenko said in a statement that Voronenkov’s killing was “an act of state terrorism on the part of Russia, which he (Voronenkov) was forced to leave for political reasons.”

Representatives of the Russian Embassy did not reply to a request for comment from CBS News, but Russian Foreign Ministry spokeswoman Maria Zakharova told the Associated Press that Russia blames the “killer regime” in Ukraine, which it says “will do its best to make sure that no one will ever know the truth about what happened.”

An opposition lawmaker, Ilya Ponomarev, speaks to press and supporters as they gather outside the Russian Investigative Committee in Moscow on Monday, Oct. 22, 2012, to protest against the arrest of opposition activists. (AP Photo/Ivan Sekretarev) AP

Ponomarev said Voronenkov believed Russia wanted him either in custody, or silenced.

The two exiled politicians saw each other often and spoke on the phone nearly every day in the months since Voronenkov moved with his wife to Ukraine, said Ponomarev. On Thursday, they planned to discuss the Interpol Red Notice -- an international alert seeking the arrest and extradition of a wanted person -- which they expected to be filed against Vorononkev, who was charged with fraud in Russia after he began publicly criticizing the government.

“We were sharing experiences, how to avoid it, and what kind of preemptive letter we have to write to Interpol to avoid putting him in the database,” Ponomarev said. “Also, he was afraid that Putin’s people would try to seize his remaining assets. His apartment in Moscow, and his country house. And we were trying to plan something for how to protect that.”