(NewsNation) — The mother of Alexei Navalny was shown her son’s body, but officials are not giving it back, the late Russian opposition leader’s spokesperson said Thursday.

Kira Yarmysh called what was happening to Navalny’s mother “blackmail” on X.

“On orders from the Kremlin, investigators set conditions for where, when and how to bury Alexei,” she said. “They want to do this secretly, without letting him say goodbye.”

Yarmysh on Saturday confirmed the death of Navalny, who had been serving a 19-year prison sentence on charges of extremism.

In December, he’d been moved from his former prison in central Russia to a “special regime” penal colony above the Artic Circle, considered the highest security level of prisons in Russia.

“Alexei Navalny was murdered,” spokesperson Kira Yarmysh said on X. “(Russia) is conducting ‘investigations’ with him. We demand that Alexei Navalny’s body be handed over to his family immediately.”

While an official death notice said his body was transported to the Salekhard morgue for an autopsy, Yarmysh said when Nalvany’s mother and lawyer went to that morgue, it was closed. 

Lyudmila Navalnaya, Navalny’s mother, urged Russian President Vladimir Putin to intervene and turn her body over to her. She filed a lawsuit at a court in the Arctic city of Salekhard, Russia’s state news agency Tass reported Wednesday.

Appearing in a video outside the penal colony where Navalny died, Lyudmila Navalnya told Putin that the “resolution of this matter depends solely on you.”

“I’m reaching out to you, Vladimir Putin. 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. 

On Monday, Navalny’s widow, Yulia, released a video accusing Putin of killing her husband, saying the Kremlin’s refusal to return Navalny’s body is part of a cover-up.

“They are cowardly and meanly hiding his body, refusing to give it to his mother and lying miserably,” she said.

Kremlin spokesman Dmitry Peskov denied a cover-up.

“These are absolutely unfounded, insolent accusations about the head of the Russian state,” Peskov said. 

Since he died, hundreds of people have been detained in Russia for trying to pay tribute to Navalny, the Associated Press reported. Authorities cordoned off some of the memorials being used as tributes. Even as police removed flowers at night, though, more kept appearing.

U.S. President Joe Biden met with Yulia and Dasha Navalnaya, Alexei Navalny’s daughter, on Thursday in San Francisco, California.

Biden, according to a readout of the interaction, expressed his admiration for Navalny’s “extraordinary courage” and “legacy of fighting against corruption and for a free and democratic Russia in which the rule of law applies equally to everyone.”

New U.S. sanctions against Russia in response to Navalny’s death are expected to be announced Friday.

The Associated Press contributed to this report.