Kiev on Wednesday admitted staging the murder of anti-Kremlin journalist Arkady Babchenko in an elaborate operation by its security services to thwart an alleged Russian plot to kill him.
There have been a number of Kremlin critics killed in Ukraine in recent years, and here is a list of some of the more high-profile cases.
- Denis Voronenkov -
Denis Voronenkov, a former Russian MP who went on to become a vocal Kremlin critic, was shot dead in broad daylight in Kiev in 2017.
Initially a federal lawmaker with the Communist Party, Voronenkov lost his seat in 2016 and then moved to Ukraine with his wife, Maria Maksakova, a well-known opera singer and a lawmaker for the ruling United Russia party, under a cloud of fraud allegations.
He became openly critical of Moscow's 2014 annexation of Crimea, testifying in a case against Ukraine's former pro-Russian president Viktor Yanukovych, who was ousted the same year.
A month before his death, he told Ukrainian media he had been repeatedly threatened by the Russian security services, saying the situation in his homeland was "like Nazi Germany".
Kiev blamed Russia's security services for his killing and detained two suspected accomplices, both Ukrainians.
Voronenkov's bodyguard shot the gunman who later died. He was a Ukrainian citizen who had fought in a volunteer battalion against pro-Russian separatists in the country's east, whom Kiev says was recruited by Russia's FSB security service.
Prosecutors also accused Maksakova's former partner Vladimir Tyurin of having ties to Russia's security services and being behind Voronenkov's killing.
Tyurin and two additional Ukrainian suspects are being sought by Kiev.
- Amina Okuyeva -
Amina Okuyeva, the doctor wife of Chechen volunteer soldier Adam Osmayev who was accused of plotting to murder Russian President Vladimir Putin, was killed last year in an attack that also wounded her husband.
Their car was hit by a hail of bullets as it was crossing a railway line in a village near Kiev.
Osmayev was accused by Moscow authorities of planning to kill Putin just weeks before the Russian leader's election to a third term in 2012.
He was held for two-and-a-half years in a Ukrainian prison but never extradited to Russia and was released soon after the 2014 pro-European uprising.
He and his wife then fought as volunteers alongside Ukrainian forces battling Russian-backed insurgents in the country's east.
Osmayev had already survived an assassination attempt in Kiev earlier in the year. The assailant was shot dead by Okuyeva on that occasion.
Her killing remains unsolved.
- Pavel Sheremet -
Independent journalist Pavel Sheremet was killed by a car bomb in 2016 while driving near his home in Kiev.
Sheremet had worked for Russian state TV but moved to live in Kiev in 2014 -- the year Moscow annexed Crimea -- over his critical views on the Kremlin's tough stance on Ukraine.
He had begun his career in his home country Belarus but left after confronting authoritarian President Alexander Lukashenko.
He founded the popular Belarussky Partizan opposition website after being detained and expelled from Belarus for his political attacks.
The reporter's murder remains unsolved.
Kiev has admitted staging the murder of Russian war correspondent Arkady Babchenko, saying it was in order to thwart a real Russian plot against him
File picture shows investigators at the site where Amina Okuyeva was shot dead outside Kiev in October last year
Belarus-born journalist Pavel Sheremet was killed in a car bombing in central Kiev in July 2016