The condition of Adam Osmayev, a participant in the anti-terrorist operation in Donbas who has been injured in Kyiv, is serious but stable, Osmayev's wife Amina Okuyeva said, adding that she shot the attacker from an award weapon.

"Everything is all right. The condition of Adam is serious but stable. I stopped the killer using the award weapon," Okuyeva said on Facebook on Thursday evening.

Osmayev and Okuyeva, officers of the Kyiv-2 police battalion who took part in the anti-terrorist operation in Donbas, were attacked in Kyiv on Thursday.

It is believed that the assailant, who introduced himself as a foreign journalist, had arranged for a meeting with the couple beforehand. "When they got into the car, the man took out a Glock pistol from a box and shot Osmayev in the chest. In response Amina fired several shots with her Makarov pistol into the gunman," the police statement says.

Detectives explained the attack with the political stance of the couple. A criminal case was opened after the attack.

Anton Gerashchenko, an advisor to the Ukrainian interior minister, said later that the killer was found in possession of a Ukrainian identification document in the name of Dakar, Oleksandr Venusovych, born 1958.

"Currently the police and security agencies are checking if such a man really exists and his life story... Most likely this Ukrainian citizen is not Dakar Oleksandr Venusovych but a completely different person who regularly travelled to Russia to receive instructions from the center," Herashchenko said.

A source in the law enforcement authorities said that Osmayev was staying at an intensive care unit with a lung injury; he was admitted to the same hospital as the assailant.

In 2012 Osmayev was detained in Odesa by Ukrainian law enforcement officers on suspicion of staging an explosion in an Odesa apartment. Investigators also suspected that he and his accomplice had been planning to assassinate the Russian president.

In September 2013 a second defendant in the case, Ilya Pyanzin, was sentenced to ten years of imprisonment in Russia after being extradited from Ukraine.

The European Court of Human Rights recommended Ukraine not to extradite Osmayev to Russia and Ukraine decided to suspend his extradition. Osmayev was released from custody on November 19, 2014 after two and a half years in jail.

In February 2015, after the death of Isa Munayev, a commander of the so-called Dzhokhar Dudayev international peacekeeping battalion fighting on the side of the Ukrainian army in Donbas, Osmayev became the battalion's new commander.