The Cost of Murder

Recently I've heard of some news that depress me greatly. I wonder how easily one can kill the other. It's a very awful case that a high school student killed his mother and cut off the head. Here are the excerpts:

The Yomiuri Shimbun
A 17-year-old high school student in Aizuwakamatsu, Fukushima Prefecture, arrested on suspicion of murdering his mother allegedly cut off her right arm as well as her head, police said Wednesday.
(May. 17, 2007)

The two other cases are:

The Yomiuri Shimbun
A 30-year-old man was arrested Tuesday on suspicion of abandoning the body of his former wife in Osaka Bay off Kobe, police said.
The police identified the body found Friday in a bag floating in the bay
(May. 16, 2007)

The Yomiuri Shimbun
A man was arrested Monday after he allegedly strangled his wife Sunday night, apparently when they quarreled over obscene images she discovered on his cell phone,.... but the charges were upgraded to murder.
(May. 8, 2007)

And here's the question:

Question: Why does a person kill the other person or himself/herself?

Economics may tell the reason: When the (marginal) benefit of killing a man is greater than the (marginal) cost of that, a murder will occur.

What's the benefit of murder? For example, by killing a person the murder can feel better. However, a murder doesn't usually think of the risk of being copped. Being caught robs him of his freedom of action and makes him fall into jail for long time. In this regard, the lifetime stream of cost of being in jail is far greater than the benefit of murder. But I wonder why one kills the other.

I think a murder can't think of his future in his life, or can only look ahead in the short run. He is shortsighted. And so he can murder. He can't behave optimally as economics suggests, and he tends to satisfy his unforeseen desire to kill a mam.

If the benefit of murder were greater than the cost of that and one really killed the other, what would prevent the killing?

From the viewpoint of public policy, one of the possibilities of preventing murder is to raise the cost to murder. For example, to put a murder to death is a strong deterrent to murder. Some pursuing the preservation of human rights disagree with this suggestion greatly, but I would ask them if a murder has the human rights. He kills a person who has the human rights as well and infringes the right of living. Should we protect his own human rights?

I suggest the death be given to a murder promptly to keep our society from awful murder. This is a better way to reduce the murder in our society.