Alexei Navalny's spokesperson says he was murdered, authorities claim 'sudden death syndrome'

The spokesperson for Russian opposition leader Alexei Navalny on Saturday declared that the Putin critic was murdered, while authorities say Navalny's death was the result of a condition called “sudden death syndrome."

"Alexey Navalny was murdered," Navalny's spokesperson wrote on the social media platform, X. "His death occurred on February 16 at 2:17 p.m. local time, according to the official message to Alexey’s mother," who was forbidden to see her son's body.

Russia’s Federal Penitentiary Service claimed that Navalny fell down and died after feeling "unwell” during a walk, according to the New York Post.

"An employee of the colony said that the body of Navalny is now in Salekhard," Navalny's spokesperson continued. "It was picked up by investigators from the IC. Now they are conducting 'investigations' with him. We demand that Alexey Navalny's body be handed over to his family immediately."

Navalny was serving a 19-year sentence on extremism charges.

In December he was moved from his former prison to a “special regime” penal colony – the highest security level of prisons in Russia – located above the Arctic Circle.