Adviser to interior minister, MP Anton Herashchenko said on air of 1+1 TV channel, Censor.NET reports.
"Voronenkov was killed by an agent of the Russian secret services planted into the Ukrainian law enforcement agency. He served there, and then received the order to eliminate 'the enemy of Russia'," Herashchenko said.
According to the lawmaker, "the investigation got very far over the day." He noted that the law enforcers established the identity and story of the killer.
"It may safely be said that Mr. Voronenkov was assassinated by an agent of Russian secret services, a citizen of Ukraine," the interior minister's adviser said.
The MP confirmed that Voronenkov's murderer was a member of the National Guard of Ukraine. He served there for 13 months, but never took part in combat operations despite having the appropriate certificate.
Herashchenko said that the killer was recruited by Russian secret services in 2014. The law enforcers are studying the history of his stay in Ukraine and interviewing his former colleagues.
Denys Voronenkov was shot dead in downtown Kyiv March 23. The killer also managed to injure Voronenkov's bodyguard. The incident took place outside Kyiv's Premier Palace Hotel.
Voronenkov was a witness in the treason case against fugitive Ukrainian president Viktor Yanukovych. In his recent interview with Censor.NET Voronenkov said that Yanukovych was a traitor "who was involved in mass slaughter, who had fled to the foreign country and urged foreign troops to slay his people. I believe this person should have received not asylum but a fair trial in Russia."