What motive triggers Torres's desire to commit an act of violence? Why did the author place this at the beginning of the article?

The event that led him to violence was the murder of his nephew, Emilio, in Chicago.

The author places this piece of information at the beginning of the article to give perspective about (and possibly sympathy for) the situation and Torres's actions. It gives reasoning for WHY he wanted revenge, and gives humanity to a story that might just be any other article about violence in American cities.