KYIV -- A court in Kyiv has placed two more suspects in the case of the 2016 killing of prominent journalist Pavel Sheremet under arrest.

The Pechersk district court ruled on December 13 that Andriy Antonenko and Yulia Kuzmenko will remain in custody until February 8, 2020. Earlier in the day, the court placed another suspect, Yana Duhar, under house arrest until the same date.

Two more suspects, Vladyslav and Inna Hryshchenko, were arrested and placed in pretrial detention in September and November, respectively, as suspects in another case.

All five suspects took part in military operations in different capacities in Ukraine's east, where government forces are fighting against Russia-backed separatists.

According to the Interior Ministry and the National Police, the group's goal was "to destabilize the political and social situation in Ukraine" by killing Sheremet.

Kuzmenko, a pediatrician and well-known volunteer, is suspected of placing the bomb under the car the night before the killing with the help of Antonenko, a musician.

Sheremet, a Belarusian-born Russian citizen who had made 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, 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.

Sheremet's mother, Lyudmila Stanislavovna Sheremet, told RFE/RL on December 13 that she did not know if the suspects are guilty or not, but that she was afraid "that innocent people may be hurt" as officials try to show they're making headway on the case.

"Pavel is gone and nothing can bring him back. Of course I need the truth.... But it is hard to judge how close they got to the truth," she said in the interview.