This is a very interesting question to ask, because actually the novel emphasises the pervasive influence of evil in the world and the way in which many "murders" occur on a daily basis, and that these murders are just as much perpetrated by characters whom we would not normally associate with criminal activity as real murderers.
You might like to think of the setting and how it ties in with this theme. The backdrop of the G8 summit and the various protests that occurred against the way in which world leaders were using and abusing their position of wealth and power to disadvantage less developed countries points out a sharply political aspect of this tale. In the same way, the novel indicates the way in which even "the common person" who might protest against such activity can be part of such a process of "murder" rather than hepling to alleviate the situation.
This backdrop therefore forms a fascinating setting for the actual serial murderer who commits his crimes during the summit. All this goes to show that this novel forces us to profoundly question what we know and assume about others to see the influence of evil acting throughout all of society.