Alexei Navalny, the Russian opposition leader who was the public face of internal opposition to Vladimir Putin, has died in prison.

The 47-year-old politician, who was serving a decades-long prison sentence on trumped-up charges at a facility around 40 miles north of the Arctic Circle, reportedly said he felt "unwell" after taking a walk and passed away shortly after.

The Russian federal prison service confirmed his death in a statement:

On February 16, 2024, in Penal Colony No. 3, the convict Alexei Navalny felt unwell after a walk, almost immediately losing consciousness, according to representatives of the department.

Medical personnel from the institution arrived promptly, and an ambulance crew was called. All necessary resuscitation measures were carried out, but unfortunately, they did not yield positive results. The emergency medical team pronounced the convict dead. The cause of death is being investigated.

Given the Russian state's notoriously loose relationship with the truth and penchant for murdering political opponents, it is unclear whether this version of events is correct or whether he was the subject of a deliberate assassination. 

Navalny was previously subject to an assassination attempt in August 2020 when he was attacked with a Novichok nerve agent during a flight to Moscow. He was hospitalized in a critical condition but eventually recovered. 

Alexei Navalny was a man of unparalleled bravery. He is a true martyr to his cause. May his legacy live on. pic.twitter.com/bXfCFA9QY0

— Ben Kew (@ben_kew) February 16, 2024

In video footage taken last month, Navalny appeared underweight with his head shaved. 

Posting on his official X account on Wednesday, his surrogates had claimed that prison authorities were subjecting him to extreme punishments, including forced isolation.

Ямальская колония решила побить владимирский рекорд холуйства и угождения московскому начальству. Только что дали 15 суток ШИЗО. То есть это 4-ое ШИЗО за менее чем 2 месяца, что я у них. Жестят.

— Alexey Navalny (@navalny) February 14, 2024

His death will come as a major blow to Russia's anti-Putin opposition and will inevitably heighten tensions between the West and Moscow as the conflict in Ukraine wages on. 

The Kremlin has yet to comment on his death, although Putin is said to have been informed.

This is a developing story. Follow RedState for more updates.