Russian opposition leader Alexei Navalny has died in prison, adding to a long line of mysterious deaths linked to critics of President Vladimir Putin. The Yamalo-Nenets regional prison service said Navalny “felt unwell” after the walk and “almost immediately lost consciousness.” Navalny, 47, one of Putin’s most high-profile and persistent critics, is being held in a prison about 40 miles north of the Arctic Circle. Navalny’s wife, Yulia Navalnaya, said Putin and his regime must be punished for the “atrocities” committed against her husband. Ukrainian President Volodymyr Zelensky said it was “obvious” that the Russian critic was killed by Putin. U.S. Vice President Kamala Harris said Navalny’s death was “a symbol of Putin’s brutality.” Russia’s foreign ministry accused the United States of making “comprehensive accusations” over Navalny’s death. Navalny is a leading critic of Russia’s “stupid” war in Ukraine, which he blames on the Kremlin elite’s “bloodlust”. Watch this video to learn more.