Ukraine's deputy prosecutor general Vitaliy Kasko announced his resignation on February 15, citing corruption and cover-ups in his office, which remains mired in allegations of ill-conduct as the country's Western backers pressure it to hasten reforms and mount a credible fight against graft.

Coming two weeks after reformist Economy Minister Aivaras Abromavicius publicly quit over alleged corruption in government, Kasko's resignation further spotlights Ukrainian authorities failure to clean up their act - even as international donors threaten to cut off the country from badly-needed credits. 

"The last straw was the yet another redistribution of authority within the Prosecutor General's Office of Ukraine," Kasko told journalists in Kyiv. "[Prosecutor General Viktor] Shokin has taken away all the functions and tools to investigate and control proceedings in cases initiated by our team."

The current heads of the prosecutor's office "turned it into a body saturated with corruption and cover-ups, while any attempts to bring in change are persecuted immediately," UNIAN news agency quoted Kasko as saying. "It's not justice and law that are in charge here, but arbitrary rule and lawlessness."

Who is Mr Shokin?

Western nations have repeatedly criticised Shokin, a close associate of Ukrainian President Petro Poroshenko, for his resistance to investigate numerous corruption allegations against former and current high-level officials and lawmakers. His one-year tenure of the post has been hallmarked by refusal to conduct reforms in both his office and in the anti-corruption sphere, say Shokhin's critics.

Geoffrey Pyatt, the US ambassador to Ukraine, in September said Shokin's office was part of the problem and not the cure. "Rather than supporting Ukraine’s reforms and working to root out corruption, corrupt actors within the Prosecutor General’s Office are making things worse by openly and aggressively undermining reform," Pyatt said during his visit to Odesa in September.

Shokin was appointed in February 2015 after his predecessor, Vitaly Yarema, resigned amid accusations that he had failed to investigate landmark crimes, including the murder of Euromaidan protesters in 2014 and the corruption schemes of former president Viktor Yanukovych and his allies.

Many commentators and politicians regard Shokin as acting under the direct influence and supervision of Poroshenko. 

"Shokin is to be found in the presidential administration more often during the day than in his own office," Andriy Sadovyi, the reform-minded mayor of the western city of Lviv and head of the Samopomich (Self Reliance) party, told bne IntelliNews in September in a warning to the government to change or be changed.

Blow to reforms or PR move?

Pyatt described Kasko's resignation as a "blow to Ukraine's reform progress", calling him a "champion for change" within the Prosecutor General's Office.

"Ukraine deserves a clean judiciary," the ambassador tweeted on February 15. "[The country] will require top-to-bottom rule of law reform to address pervasive corruption and cronyism. [The] United States will continue to assist those in [the] prosecutorial domain committed to operating under new rules."

Meanwhile, Shokin's aide Vladyslav Kutsenko said Kasko's resignation was a "PR action" and merely reflected his failure to cope with his duties.

"He had all the levers in his hands to [...] demonstrate to society his activities on the international issue, on sanctions, on the fight against corruption. [...] As they say, a bad workman blames his tools," Kutsenko told the Ukrainian 112 television channel.

In any case, the latest resignation will only strengthen the resolve of Ukraine's international backers to take a hard line with the authorities in Kyiv over their failure to uproot endemic corruption.

Ukraine's main donor, the International Monetary Fund (IMF), has already warned that its current $17.5bn support programme risks being derailed by the poor performance of the national authorities.