Former Russian MP Denis Voronenkov has been shot dead outside a hotel in the centre of the Ukrainian capital.
Voronenkov and his bodyguard were leaving the Premier Palace hotel when they were attacked.
Witnesses spoke of hearing seven shots being fired outside the hotel.
The bodyguard fired back and managed to injure the attacker, getting wounded in the process.
Voronenkov was a former Communist MP and had moved to the Ukraine for fear of being persecuted by Russian security agencies. He was also accused by Russian opposition leader Alexei Nalvaney of fraud.
Voronenkov was a controversial figure and openly criticised Vladimir Putin and Kremlin policy in Ukraine.
Kiev Police Chief Andrei Krishchenko said the murder had most likely been a contract killing.
Mr Voronenkov also gave evidence in a a high treason case against former Ukrainian President Viktor Yanukovych who was removed from office a few months ago. Furthermore, he criticised Russia’s annexation of Crimea, saying that it was illegal.
Both the bodyguard and the attacker were injured and are now being treated in the hospital.