Ukrainian police have detained five suspects in connection with the killing of the prominent journalist Pavel Sheremet three years ago.



Sheremet's killing in a car bomb blast in predawn Kyiv underscored concerns of a climate of impunity for attacks on journalists and others who challenge the authorities, and the government has faced persistent criticism over the perceived lack of progress in solving the case.

Addressing reporters in Kyiv on December 12, top Interior Ministry and national police officials said that the suspects include a couple -- Vladyslav and Inna Hryshchenko, who took part in supporting Ukrainian armed forces in fighting Russia-backed separatists in Ukraine’s east -- as well as a musician and former special operations combatant, Andriy Antonenko; a pediatric surgeon who helped troops in the east as a volunteer, Yulia Kuzmenko; and a military physician, Yana Duhar.

WATCH: Pavel Sheremet: The Life And Violent Death Of A Journalist (originally published in July 2017)



Deputy national police chief Yevhen Koval said the suspects had aimed to destabilize the “social and political situation in Ukraine” with the high-profile murder.

Interior Minister Arsen Avakov told reporters that the investigation isn’t closed and several “sub-variants” of the murder motive are being investigated, including Russia’s possible involvement.



Officials said that 35 similar crimes had been committed in Ukraine in recent years, adding the suspects may have been involved in two of these other attacks.



Avakov said the arrests follow a “difficult and persistent” investigation, which yielded results he described as “shocking.”



“The public should understand the difference between patriotism and treason,” Avakov said.



One of the suspects, Vladyslav Hryshchenko, had six past convictions for extortion and robbery, and, according to police, was an explosives expert.



Sheremet, a Belarusian-born Russian citizen who had made the Ukrainian capital, Kyiv, his permanent home, was leaving his apartment to head to the studio where he hosted a morning radio program when an improvised explosive device planted under the vehicle he was driving exploded on July 20, 2016.

Koval said Antonenko and Kuzmenko were accused of planting the explosive device under Sheremet’s car. He said investigators had relied on video footage from surveillance cameras and other evidence.

Assisting investigators was British forensic gait analyst Ivan Birch, the national police official said.



“Birch processed the materials presented to him, which took a certain amount of time, and provided his conclusions,” Koval said.

Antonenko, denying any role in the killing of Sheremet, managed to post a social-media plea as police came to detain him.



"I am being accused of killing Sheremet. Right now [...] Help!" he wrote on Facebook.

Ukrainian President Volodymyr Zelenskiy and Prosecutor-General Ruslan Ryaboshapka, who were present at the December 12 press conference, expressed thanks to the national police and the Interior Ministry for their “good work” in investigating the high-profile killing.



Zelenskiy commended police for their work but added that questions remain.



"The probable murderers are detained today. As you have seen yourselves, I am convinced that we have been given very many answers today, thank God. But one question still remains: Who ordered [the killing]? I am convinced that an answer to this question will definitely be found."

The chief editor for Ukrayinska Pravda, Sevhil Musayeva, the local media outlet where Sheremet was simultaneously employed at the time of his murder, issued a restrained statement after the police briefing.



“We welcome the fact that the investigation is ongoing, and the case wasn’t forgotten. To be honest, the version outlined by the investigation shocked us. We currently are treating the information provided with caution,” she said on Facebook.

The 44-year-old Sheremet, who was honored by the Committee to Protect Journalists with the International Press Freedom Award in 1998, was well known as a hard-hitting reporter and commentator who had worked at prominent media outlets in Belarus, Russia, and Ukraine during his decades-long career.



Often critical of political leaders, he had received threats and been harassed on several occasions. His Belarusian cameraman Dzmitry Zavadski was abducted and killed in 2000 after the two returned from a reporting trip in Russia's Chechnya region.



Sheremet was stripped of his Belarusian citizenship in 2010 while he was living in Russia, where he had moved in 1997 to avoid persecution following his reports criticizing Belarusian President Alyaksandr Lukashenka's government.

With reporting by AP