The assailant who allegedly shot and killed a former Russian lawmaker in Kiev Thursday has died in a hospital, according to Ukrainian news reports.
The Ukrainian president called the murder of Denis Voronenkov an "act of state terrorism" by Russia, an accusation that was quickly rejected by the Kremlin.
President Petro Poroshenko said Voronenkov's killing "clearly shows the handwriting of Russian special services shown repeatedly in various European capitals in the past."
In a statement released by his spokesman, Svyatoslav Tsegolko, Poroshenko described the victim as a key witness who gave testimony about "Russian aggression" to the Ukrainian authorities.
The gruesome shootout took place on a busy streetcorner in the center in Kiev at approximately 11:30 a.m. Thursday, the Kiev Post reported. Voronenkov, 45, was shot twice in the head as he was leaving the Premier Palace Hotel.
Russian President Vladimir Putin's spokesman, Dmitry Peskov, dismissed the claim of Russian involvement in the killing as "absurd" in a statement carried by Russian news agencies.
Voronenkov, a former member of the communist faction in the lower house of Russian parliament, had moved to Ukraine last fall and had been granted Ukrainian citizenship.
He testified to Ukrainian investigators as part of their probe into the activities of the nation's former Russia-friendly president, Viktor Yanukovych, who was ousted by massive protests in February 2014.
Voronenkov, who had obediently toed the Kremlin line while serving as lawmaker, became a vociferous critic of Russian policies after his move to Kiev.
The unidentified gunman also wounded Voronenkov's bodyguard, who fired back and wounded the assailant.
Witnesses told the Kiev Post they heard 6 to 12 gunshots. A gun was found lying next to Voronenkov’s head, according to the newspaper.
The attacker was seen lying on the ground a few feet away from Voronenkov, face down and wearing a gray sweatsuit and gloves.
Voronenkov left Russia with his wife, singer Maria Maksakova, who was also a lawmaker. He said he had to leave Russia because of persecution by Russian security agencies and had renounced Russian citizenship.
After Voronenkov's move to Ukraine, Russian investigators have filed fraud charges against Voronenkov in connection with his business activities.
Voronenkov, a father of two, was reportedly on his way to a meeting with another exiled Russian lawmaker, Ilya Ponomarev, when he was attacked.
"He was heading to a meeting with me. I have no words," Ponomarev tweeted.
Members of the Russian parliament were quick to reject Ukrainian allegations that Voronenkov could have been killed over any betrayal of Russia.
Nikolai Kovalyov, the former Russian security chief who is a lawmaker, told Russian state television that the killing could have been rooted in a business dispute.
Peskov said that Putin was informed about Voronenkov's killing and voiced hope that Ukrainian authorities would solve the crime. He added that Voronenkov's widow was welcome to return to Russia.
The Associated Press contributed to this report.