There is never a void in nature. There is always repercussions, potential counter-attack from others.
Some people have more value than others. Some people have families and societies. Thus the family or society will retaliate against you. Revenge is Natural Law. However, low value people, homeless men, bums, dregs, are worth less. Arguably you will face less retaliation, and in some cases, no retaliation at all. Likewise, killing children or women is deemed more heinous and will face more retaliation.
So basically my point is, based on the value of some people, you will face retaliation for many different reasons. If you kill a factory worker, for example, then the factory employer loses an employee. You cost the factory a laborer. On an abstracted level, society has lost a worker and member. Thus society imposes laws, fines, judgments, and retaliation. Society will employ police to find and capture you, lawyers and judges to sentence you, etc.