Additional evidence is needed for the murder case of journalist Pavel Sheremet to go to trial, Ukrainian Prosecutor-General Ruslan Ryaboshapka said on January 30.
"The volume of compiled evidence isn't enough," he told the Interfax news agency in an interview.
Ryaboshapka said that, in order to determine whether the suspects were guilty or innocent, "written instructions were prepared for the investigating prosecutors and the terms of the investigation were accordingly set."
Sheremet, a Belarusian-born Russian citizen who had made Kyiv his permanent home, was leaving his apartment to head to a broadcast 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, killing him instantly.
Sheremet's killing underscored concerns of a climate of impunity for attacks on journalists and others who challenge the authorities, while the government has faced persistent criticism over a perceived lack of progress in solving the case.
Investigators suspect three people of involvement in the murder, all of them with ties to the war taking place in two eastern regions of Ukraine.
They are former special operations Sergeant Andriy Antonenko, army medic Yana Duhar, and pediatric surgeon and volunteer Yuliya Kuzmenko.
Police have also named two persons of interest in the investigation -- married couple Inna and Vladyslav Hryshchenko.
William Taylor, the former U.S. charge d'affaires in Ukraine, has suggested Interior Minister Arsen Avakov isn't certain that the people who were charged with the murder are guilty.
Reporters Without Borders (RSF), a France-based media watchdog, has called the probe a "flawed three-and-a-half-year investigation."
In a statement on January 10, RSF raised concern about "inconsistencies in the evidence for the Ukrainian authorities' claim to have solved [Sheremet’s] murder,” and urged them to “continue the investigation and to be more transparent as they do so."
This investigation "offers the opportunity to really begin combating impunity," said Jeanne Cavelier, the head of the Paris-based media freedom watchdog's Eastern Europe and Central Asia desk.
"Not just the perpetrators but also the instigators should be identified and brought to trial," Cavelier insisted.
Sheremet's mother, Lyudmila Sheremet, told RFE/RL in December that she does not know if the suspects are guilty or not, but that she is afraid "that innocent people may be hurt" as officials try to show they're making headway in the case.