Navalny's spokesperson, Kira Yarmysh, declared Navalny was murdered via a social media post on X Saturday, one day after Russia’s prison agency announced his death on Friday. Navalny was being held at the IK-3 penal colony, also known as "Polar Wolf," in Kharp, Russia.
The agency said he felt unwell after a walk and lost consciousness. An ambulance arrived to rehabilitate him, but he died, per a statement released. Navalny was 47 years old.
He had previously run for office to advocate for reforms against what he claimed was corruption in Russia. He also organized anti-government demonstrations and was the victim of an alleged assassination attempt in 2020, when he suffered poisoning from a suspected Novichok nerve agent.
Navalny remained in a coma for several weeks while doctors in Germany fought to keep him alive. He accused Putin of being responsible for his poisoning.
Navalny later returned to Russia in 2021. He was immediately arrested by authorities and later sentenced to 19 years in prison on extremism charges. His team has repeatedly raised concerns about his treatment following his return, and Navalny said the charges were politically motivated.
Fox News' Timothy Nerozzi and Greg Norman contributed to this report.