BERLIN The wife of Russian opposition leader Alexei Navalny said on Wednesday that laboratory analysis of smuggled biological samples found he was killed by poisoning while incarcerated at an Arctic prison in February 2024. Navalny, President Vladimir Putin 's most formidable critic for years, died in mysterious circumstances while serving a 19-year prison sentence on a string of charges widely seen as retribution for his opposition. The charismatic anti-corruption campaigner had rallied