Yulia Navalnaya, widow of Russian opposition leader Alexei Navalny, has dismissed the official explanation of her husband's death, which attributes it to a 'combination of diseases,' including cardiac arrhythmia and various chronic ailments. She insists that Navalny was murdered and is demanding a criminal investigation, alleging the authorities are covering up the true cause of his death. Navalny died suddenly on February 16 in a Siberian penal colony while serving a lengthy sentence on charges he claimed were politically motivated. The Kremlin denies accusations that President Vladimir Putin was involved in his death. Navalnaya has published an official letter stating no criminal circumstances were found, and criticizes the investigative process as inadequate.