We are not cave dwellers anymore, we live in the age of technology. When someone needs a car, he does not need to build it. He can buy it. When someone needs a murder, he himself does not need to kill. He can order it.
I believe we are still so innocent. The species are still so innocent that a person who is apt to be murdered believes that the murderer, just before he puts the final wrench on his throat, will have enough compassion to give him one sweet cup of water.
The boys with their feet on the desks know that the easiest murder case in the world to break is the one somebody tried to get very cute with; the one that really bothers them is the murder somebody only thought of two minutes before he pulled it off.
Under the rules of a society that cannot distinguish between profit and profiteering, between money defined as necessity and money defined as luxury, murder is occasionally obligatory and always permissible.