The enemy in such a war is often nothing more than scared fourteen-year-old boys holding big guns. Seeing perpetrators this way extends compassion even to them without excusing the violence. In the midst of evil, there are still unexpected flares of goodness and dignity among those facing death.
Distant people fail to act on suffering mainly because they don't understand it, not because they don't care. Once they grasp what is really happening, they will do what they can to steer the world back toward kindness. The witness's job is therefore to make the situation understood, not merely reported.
A government can try to depopulate a region by force, using an uprising as its pretext. Against that, a survivor's patient and humane telling of what happened makes a case more compelling than bombs and bullets. Even after prison, the witness keeps speaking because the story is his weapon.