The Russian government has announced the death of Alexei A. Navalny without offering many details. Here is what we know about Mr. Navalny’s fate and what happens next.

Cause of death: In announcing Mr. Navalny’s death, Russia’s prison service said that he felt suddenly unwell during a walk. The medical workers who had arrived to attend to him in an ambulance had “performed all the required resuscitation procedures,” without success.

A doctor working near Mr. Navalny’s prison above the Arctic Circle told the independent Russian news outlet Mediazona that the closest ambulance team is 35 kilometers, or 22 miles, from the prison. By the time it would have arrived, a patient in severe distress would already be dead, said the doctor, who spoke on condition of anonymity. “Who were they resuscitating?” he added.