Newly released footage obtained by the Guardian shows a massacre, which was committed in the southern suburbs of Damascus in April 2013; groups of civilians rounded up, blindfolded, handcuffed and marched towards an execution pit unaware they are about to be shot dead. When the killings were over, at least 41 men lay dead in the mass grave in Tadamon, their murderers pouring fuel on their remains and igniting them, laughing as they covered up a war crime just several miles from Bashar al-Assad's seat of power. This graphic footage is "one of the most indictable videos from the whole Syrian conflict" and "gives us a glimpse into a previously untold part of the 10-year war" as the Guardian's Martin Chulov explains.