Yulia Navalnaya, widow of leading Russian opposition figure Alexei Navalny, said on Thursday that the Russian authorities had offered no convincing explanation for his death in a penal colony six months ago. In a video posting on X, Navalnaya said she had received a three-page document stating that Navalny’s death had not been the result of a crime and that there were consequently no grounds for a criminal investigation. Navalny died in a Siberian penal colony in the Arctic Circle on February 16 while serving a 19-year sentence on what he termed politically motivated charges. The prominent act…