The mother of Russian Opposition leader Alexei Navalny has filed a lawsuit at a court in the Arctic city of Salekhard contesting officials’ refusal to release her son’s body, Russia’s state news agency Tass reported on Wednesday.

A closed-door hearing has been scheduled for March 4, the report said, quoting court officials.

Lyudmila Navalnaya has been trying to retrieve her son’s body since Saturday, following his death in a penal colony in Russia’s far north a day earlier. She has been unable to find out where his body is being held, Navalny’s team reported.

Navalnaya appealed to Russian President Vladimir Putin on Tuesday to release her son’s remains so that she could bury him with dignity.

“For the fifth day, I have been unable to see him. They wouldn’t release his body to me. And they’re not even telling me where he is,” a black-clad Navalnaya, 69, said in the video, with the barbed wire of Penal Colony No. 3 in Kharp, 1,900km northeast of Moscow.

“I’m reaching out to you, Vladimir Putin. The resolution of this matter depends solely on you. Let me finally see my son. I demand that Alexei’s body is released immediately so that I can bury him like a human being,” she said in the video, which was posted to social media by Navalny’s team.

Russian authorities have said the cause of Navalny’s death is still unknown and refused to release his body for the next two weeks as the preliminary inquest continues, members of Navalny’s team said. They accused the government of stalling to try to hide evidence. On Monday, Navalny’s widow, Yulia, released a video accusing Putin of killing her husband.