Russian lawyer and opposition leader Alexei Navalny has died in prison at age 47 according to authorities from the nation’s prison service, per NBC News.

According to the outlet, a statement released on Friday by the Russian prison service for the Yamalo-Nenets region, where Navalny was transferred to, said that he “felt unwell after a walk, almost immediately losing consciousness.”

“The facility’s medical workers immediately arrived at the scene and an emergency medical team was called in,” the statement continued. “All necessary resuscitation measures have been carried out, but they did not yield positive results. Emergency medics confirmed the death of the convict.”

However, according to NBC News, nothing seemed out of the ordinary for him physically when he had appeared in court just a day prior. His mother, Lyudmila Navalnaya, saw him on Monday (Feb. 12) and described him as being “alive, happy, and healthy,” in a Facebook post shared Friday, per Reuters. Navalny’s wife Yulia Navalnaya stated at the Munich Security Conference on Friday that she is still unsure if the news is true, explaining that “we can’t really believe Putin and his government,” per USA Today. However, she urged those in attendance “to unite and help punish the Russian regime.”

A known critic of Russia’s President Vladimir Putin and corruption within the Kremlin, Navalny was instrumental in protests and campaigns against the nation’s government, per CNN. He was ultimately hit with a 30.5-year jail sentence across various charges, which he has argued are “politically motivated” in order to prevent him from gaining further support against Putin.

According to NPR, Navalny was poisoned in 2020 with a nerve agent described as being in the Novichok family, which was discovered while he was hospitalized in Germany. After returning to Russia from Germany in 2021, he was arrested, and remained in prison until his death. The Russian government has rejected claims that they were involved in him being poisoned,

He had gone missing in December, and was eventually found at the IK-3 penal colony located in Kharp that is called “Polar Wolf,” per CNN.

His story became the focus of the 2022 documentary Navalny, which won Best Documentary Feature at last year’s Oscars. The film is described as “an eye-opening documentary chronicling the investigation into the shockingly brazen assassination attempt of Russian opposition leader Alexei Navalny,” per its synopsis.

Decider contributor John Serba urged prospective viewers to “STREAM IT,” describing it as “essential” and “Oscar well-deserved.

Navalny is streaming on Max. Monthly plan options range from $9.99/month to $19.99/month. Prospective customers can check out further pricing information on Max’s website.

Watch the trailer for Navalny above.