Riot police ordered Iranian opposition leader Mir Hossein Mousavi to leave the mourning ceremony commemorating Neda Agha-Soltan, whose death under their force was disseminated to the world via YouTube, and others killed in the post-election violence on June 12. The New York Times reports that hundreds of people gathered around Agha-Soltan's grave, which Mousavi attempted to approach before police forced him back into his car. As Mousavi drove off, police and mourners argued. Some reports say police arrested mourners and tried to scatter them. It's significant that this is the 40th day since Agha-Soltan's death. As the Times put it, "The 40th day marks an important Shiite mourning ritual, and similar commemorations for dead protesters fueled the demonstrations that led to the Islamic Revolution in 1979."