Examples of a stage of genocide

So far in the book Forgotten Fire,  I have seen at least three examples of the seventh stage of genocide: extermination. The book is about the main character, Vahan, who is an Armenian, uses his inner strength to escape the Turkish Gendarmes, which are inciting a genocide that is denied to this day. The first example is near the start of the book, Vahan and his family is brought outside of their house in the front yard. They are first questioned then the lead Gendarme dismisses them, but stops Vahan`s two older brothers, Tavel and Diran and asks them how old they are. They answer that they are both over 18, and the gendarmes lead them over to the garden wall and proceed to murder his older brothers. To make sure they are dead, the leader then shoots them each through the head and leaves. Later after that the gendarmes return and escort them to an inn. This leads to the second example, because as they leave, vahan and his family see a large mound of bodies with his recently deceased sister on top. Shortly after they leave, the third example of extermination happens. The Turkish Gendarmes lead the Armenians to a river that is stuffed with dead bodies and what water there is poisoned. They invite the Armenians to drink; the gendarmes go up behind them and shoot them through the head. Vahan`s grandmother was one of the ones that died here.